Eco-Driving promoted by the European Commission

High fuel prices are wreaking havoc in Europe, some call for tax exemptions others go on strike. The structural constraints affecting oil supply are becoming to much to bear for Europeans, especially those more reliant on the automobile.

But before going out for a demonstration against who ever you may think is responsible for high fuel prices, there are a few things you can do to ease the pain: it's called Eco-Driving.
Crossposted at the European Tribune.

Together with Europia (European Petroleum Industry Association) the European Commission has launched a campaign to promote energy efficient driving. Leaflets with a roll of tips that help drivers reducing their fuel consumption will be made available at filling stations all across Europe. Some 45 000 stations will receive the leaflets in one the biggest public information campaign I can remember (surely the biggest on Energy). The press from the Comission anouncing the campaign can be read in full here.

Andris Piebalgs wrote in his blog about this “intelligent driving”:

I made recently a short test with an eco-driving simulator. By applying all eco-driving tips, a normal driver is able to reduce his energy consumption in an urban circuit from 7.3 l/100km to 5 liters. That means, at a price of 1.40 € per litre of gasoline and 15 000 km per year, that the driver is saving 500 €. Let’s imagine that the drivers would apply just some of the tips, we are still speaking of impressive savings, in money terms for the citizens and in CO2 emissions for the planet.

Eco-driving entails no investment, no need for sacrifice. It is simply a matter of responsible behaviour, keeping in mind some principles when driving, which make sense and are beneficial in all respects: not only for our planet and economy, but also for our health and our safety. One could ask: Why do so few people eco-drive? The reply is quite obvious: because we have not been educated to do that! Only recently are eco-driving principles really becoming part of the syllabus for obtaining a driver’s licence. That means that only new drivers have been taught to drive intelligently.

A website was made promoting the campaign on-line. Go there and click your flag of choice, you'll be presented with some funny cartoons exemplifying the tips (nice to send around to your friends perhaps).

Here are the 10 tips being promoted in the leaflet [pdf 2.9 Mb]:

Save more than fuel

10 tips to help you drive more efficiently.

  1. Keep your car well serviced and check the oil level regularly.
    Correctly maintained cars can operate more efficiently and help reduce CO2 emissions.

  2. Check your tyre pressure every month.
    Under-inflated tyres can increase fuel consumption by up to 4%.

  3. Remove unnecessary weight from your boot or back seats.
    The heavier the car, the harder the engine has to work and the more fuel it consumes.

  4. Close your windows, especially at higher speeds, and remove empty roof racks.
    This will reduce wind resistance and can lower your fuel consumption and CO2 emissions by up to 10%.

  5. Use air conditioning only when necessary.
    Unnecessary use increases fuel consumption and CO2 emissions by up to 5%.

  6. Start driving soon after starting the engine and turn off the engine when stationary for more than one minute.
    Modern engines enable you to just get in and go, thus reducing fuel consumption.

  7. Drive at reasonable speeds and above all, drive smoothly.
    Every time you accelerate or brake suddenly, your engine uses more fuel and produces more CO2.

  8. When accelerating, change up gears as early as possible.
    Higher gears are more economical in terms of fuel consumption.

  9. Try to anticipate traffic flow.
    Look at the traffic as far ahead as possible in order to avoid unnecessary stopping and starting within the flow of traffic.

  10. Consider car sharing for work or leisure.
    You will help reduce congestion and fuel consumption.

Following these tips will not likely have any impact on world oil prices, but they are one step that each EU citizen can take to ease the dependence on oil and at the same time diminish the economic backlash from high fuel costs.

Finally there's a video worth watching on EUtube on the subject (possibly good educational stuff too):

It's about awareness.

The best way to get awareness about 'Eco Driving' is to obtain a bicycle and ride it around for some distance both in town and a little further afield. Then, as in a way that will never be made viscerally apparent to you in a car, you will instinctively understand:

the importance of correct tyre type, condition and pressure
the importance of not carrying unneccessary weight
the effect of wind drag
the importance of not pedalling when stationary!
the importance of smooth, fluid progress and not accelerating or braking without good reason
the importance of changing gears for the optimum motion with least effort
the importance of anticipating traffic flow
consider a tandem??

It amazing what you learn when you provide the motice power instead of 150 BHP under the bonnet.

Simple really, but shows how fossil fuels disconnect us from underlying physical reality. That of which every cyclist is acutely aware.

Human and e power assist

And once you've obtained a bicycle and ridden it, don't get back into your car except in an emergency.

Great post, especially: "the importance of not pedaling when stationary!"

I walk to work much of the time and am constantly struck by how loud/wasteful/rude cars and people in cars are. When I'm in my own car, of course, none of that applies. :-)

All good stuff. Couple of things they don't mention: Coasting up to red lights (saves fuel, and gives the light more time to change as you approach); and lowering your speed on faster routes - I estimate I save about 15% on the motorway by driving at 60-65mph rather than the 70-75mph that most drivers do. Much less stressful too.

35 mph may be the most efficient

35 is considerably less efficient than 43 in my car.  At 35, my transmission will only upshift to 4th and the engine is turning about 1700 RPM; at 43, I'm solidly in 5th and the engine turns around 1400 RPM, with far less friction.  The difference per the trip computer is about 45 MPG to ~60 MPG.

Transmissions differ, but with automatics, the most efficient speed is the lowest speed at which the torque converter lockup clutch engages in top gear. 45-50 mph sounds about right.

With a manual, I've been short-shifting in city driving and it seems to give about a 5-10% improvement. City traffic is slow enough that the lack of acceleration doesn't matter. There are places where you need more acceleration, like to safely merge onto freeways, so use common sense here.

I think you are right, unfortunatly one of my vehicles is programmed only to "lockup" at 50mph. If I dont get over 50 it will NEVER lockup. Its possible to reprogramm the Transmission to lockup earlier and even short shift. I wish more cars would have transmission modes, like economy and sport. of course manual transmission cars dont have that problem...

That's CORRECT !

I've driven many vehicles, trying eco-driving and the most efficient speeds are 47miles/hour (80km/hour) and ABOVE !

Ford Excort - Manual 5th gear does not work well below 40mi/h .
My Volvo switches to overdrive at 47.5mi/h.
My Chrysler Town&Country switches to overdrive at 46 mi/h. It has fuel calculator, that shows the most efficient speed at 62mi/h.

But if you drive at the limit, automatic thransmissio switches back and forth, using more energy. 50mi/h+ is the answer.

Mmmm...does everyone else live in a place called Happyville? Around here, if you coasted to the light, one or two other drivers would try to pass to get to the light first; if you tried driving 10 mph below the speed limit, you would be either ticketed, receive multiple obscene gestures, or be run over by a Freightliner -- none of these possibilities being less stressful...

Today I got a fill up at Costco, where there are 10 or twelve fueling bays, and each bay had a six to eight car line. Probably half the cars were full size vans, large pickups, or regular size to large size SUVs (and I include my old VW Bus and its 17 mpg in that group).

The local going and coming is terrific, and no mere $5, $6, $7, or $8 gas is going to stop it, and I wonder if it will even slow it down.

Well we have only seen $4 gas and the reaction...

$5 $6 $7 $8 will be different

"if you tried driving 10 mph below the speed limit, you would be either ticketed, receive multiple obscene gestures, or be run over by a Freightliner"

Not sure where your "Around here" is, but we took a road trip around North America last fall, driving 60 mph the entire time. We did get passed by just about everyone, everywhere. However, the only time we felt antagonism was on the autoroute near Montréal - we've never seen such impatient drivers...

Besides the improved fuel mileage, being slightly slower allowed continuous use of the cruise control. It made for a very relaxing journey.

Now we're seeing more and more drivers taking it slow in our area, as low as 50 on the freeway, even some of the big rigs.

Rick in WA, USA

haha, Montreal drivers are a special breed. The Island of Montreal is the only place in Canada that I know of (I don't know much) where drivers aren't trusted to execute a 'right on red' without killing someone. Having said that, Montreal is one of my favourite cities, a truly cosmopolitan city bursting with culture and creativity.

In Ottawa I've noticed that 90-100km/h on the highway is becoming increasingly acceptable, but we are about the politest city around. I've often mused that in a disaster Ottawans are more likely to die of politeness than anything else... we're like a city full of those two excessively polite loony toons squirrels.

"haha, Montreal drivers are a special breed"

That is so true! We were actually LOL at the gestures and antics of the drivers - we honestly thought they were going to blow a gasket... Relax, people!

"Montreal is one of my favourite cities"

We like Montréal as well - I was born there, and still have family in the city.

We visited some cousins in Ottawa, too, and had a beautiful afternoon (28C on 22 Oct) in a park on the river. Everyone seemed to be enjoying themselves.

Rick in WA, USA

Having spent a good part of my life in Montréal I can attest that most pedestrians appreciate the no-right-on-red rule. Drivers here are indeed quite aggressive at times. If you try to stick to the speed limit on an open road to save fuel, someone is bound to tail you closely, or attempt a reckless bypass manoeuvre. This may be accompanied by honking and improper gestures, all in good fun. This is why I always advise visitors to the city to avoid renting a car and stick to the public transit system here, which is truly exceptional (for North America).

In the European Union, LGVs* are limited by law to 56mph (90km/h) and buses are limited to 62mph (100km/h). Newer LGVs are fitted with a governor, a device which physically limits the speed. The upshot of this is that cars can safely drive at 56mph, and if you're feeling brave you can drive in the slipstream of a truck and save even more fuel.

*LGV = Large Goods Vehicle, a truck heavier than 3500 kg (7716 lbs)

I'm in Vancouver, WA, and it really is a madhouse on the roads. My daughters live in Ellensberg, where it is NOT a madhouse, and I love driving there. However, when they come here, they can't stand the traffic (the first comment is always, I can't get used to driving in town at over 25 mph). I wonder if the difference in "attitude" is driving on freeways vs. driving locally, in town...

Gas is now over $4 a gallon just about everywhere but Arco, and diesel is $4.95 is some places. I was out driving this morning, and they're still going hell-bent-for-leather...those Escalades...those F-350s...

I can assure you that what looks like a madhouse to you will look like incredible sanity to me. When I visited Cincinnatti and then Saginaw, MI I was amazed how seriously Americans took the STOP signs.

I lived in Singapore for 6 years and was amused that the Europeans and Australians complained that Singaporean drivers were aggressive. Coming from India, I was amazed that drivers did not honk, stopped for you at pedestrian crossings (even at 12:00 midnight), drove in lanes and were generally courteous.

Back here in India, I cannot believe at what passes off as traffic. People honk all the time, will not stop for a pedestrian (they would run over their grandmothers if it saved them 5 minutes!) and jump lights at will.


Here in the UK savage fines for speeding mean that you rarely get hassle when you stick to the speed limits, although most usually go a few MPH faster.
Ten years ago that was not the case, and driving at the speed limit would have led to considerable aggression from other drivers.

During the oil problems of the 70's there were numerous articles about driving techniques to save fuel. I routinely coast to red lights and often have conserved some forward momentum when the light changes. This will also save brake linings. It is amusing to watch someone pass me and then throw on the brakes. Also it is not difficult to drive 55 to 65 when there are two or more lanes.

We bought a Prius for my wife, and the monitor on the dash has provided excellent feedback on low-consumption driving that I've applied to my truck (a '94 Toyota 6-cyl). I coast whenever possible, including downhill with the clutch disengaged and engine at idle, use cruise whenever possible, drive no faster than the speed limit, keep the tires at or just slightly above recommended pressure, use the highest gear possible, etc. It is rated for 15 mpg city and 18 hwy, I generally get 20 mpg with mixed driving. I am going to be upgrading to a high-airflow filter and capacitor based sparkplugs next, based on lab data (most of the crap sold to improve gas milage is just that - crap, but some things work).

We recently drove the Prius from Albuquerque to Calgary and back, av 50 mpg, kept the cruise at 5-10 mph below the speed limit on the highway. A few people got excited and seemed to feel more inclined to hurry us along rather than just passing, but no real problems overall. I've just learned to ignore people when coasting to stoplights in the city. It is actually an interesting experience to watch people zip around you to dash that last 40 meters to the stoplight then jam on the brakes.

I would probably make an exception to all this in Montreal....I'm still too young to die!

I agree with KiltedGreen re cycling behaviour for learning energy conservation.

Many useful performance benefits are of course frowned upon in the UK or worse would constitute 'negligent driving' in any accident.

When I took my test it said that not following the highway code reccomendations could be used against you in litigation.

For ~ 15 years of their availablity, it was illegal to use flashing rear bicycle lights in the UK - despite the fact they work better and batteries last longer. This is the mentality we are up against.

2 obvious real ways to add 10 - 20% to MPG are:

With a manual box, coast along wherever you would freewheel if you were a cyclist.

Obviously this works best in rolling low hills or light urban driving, not when doing a constant 60mph for miles.

Inflate tyres to the max pressure on the tyrewall [this one will have ambulance-chasers salivating].

Both would cause legal problems in the UK/EU

Then again, if our Euro MPs actually cared about economic driving rather than lobby perks, they could just take the catalytic convertors from EU cars and - hey presto! - 5-10% MPG magically re-appears. How much fuel has that little cockup wasted over the last 15 years??

A reasonable compromise on tyre pressure is to inflate them to around 4-5psi over recommended.
Just pumping them all they can stand is not sensible, as staying alive is an even greater priority than fuel economy, and you don't want to loose traction.
However, manufacturers recommended pressures are often biased towards ride comfort rather than economy, so some over-pressure should be fine, assuming that you are not going to be screaming at maximum speed round every bend, which would rather defeat your fuel economy objective anyway.
Bear in mind that if you inflated the tyres when cold, then the pressure will increase as they warm up, and vice versa.

An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi, they could be damaged more easily when encountering potholes or debris in the road, as well as experience irregular tread wear. Higher inflated tires cannot isolate road irregularities as well causing the vehicle to ride harsher and transmit more noise into its interior. However, higher inflation pressures reduce rolling resistance slightly and typically provide a slight improvement in steering response and cornering stability. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures.

As far as I can tell, pressure recomendations are meant to maximize performance including protecting the rest of the suspension, having the longest tire life while doing the best for fuel economy. Advice to overinflate should likely be ignored.


This is similar to "Hypermiling" beginning to be known in the US. See for more.

I agree with the concern on overinflating the tires, but keeping them at the recommended pressure or a 1-2 PSI higher seems to make a difference. With a manual transmission, coasting at idle saves quite a bit compared to remaining in gear. Through various techniques, including keeping the speed to 40-45 MPH on back roads and no more than 60 on the highway, I've manage to gain 20% over my car's average MPG. Not bad.

Chris from Boston, MA

Re Cat Converters:

Ha Ha!

Here is what you do:

1. Install Cat.
2. Go and Get your Annual MOT
3. Pass MOT.
4. Go home, remove CAT and replace with a piece of dumb pipe. (20 minutes work)
5. Repeat on an annual basis.

Good for fuel economy, saves degradation of the CAT (£500 apiece), but the best of all: gives the finger to our EURO elders and betters.

Been that way in rural Britain for years. Probably the same in Rural France, Belguim, Germany, Italy,...(insert Euro Country here).

Just because they make rules, doesnt mean you actually have to be a slave.

Trouble is, PC Plod has cottoned on to it. Hence the roadside checks.

Still, for Plod it is a hell of a lot safer than chasing muggers and rapists.

Interesting that they don't mention the possibility of "drive less or not at all". Apparently we are all disabled and cannot move without the assistance of our personal powered machine :)

40% of journeys in the US and Australia are under 3km...

edit 1: according to the ABS, the proportion of journeys by purpose are... (figures shortly)

edit 2: [source, ABS] The following is the data of purpose of journey by car from 1992, the most recent year available for such data for Australia as a whole.

Purpose of journey % % minutes
Shopping 46.2 25.7 13
Work(a) 41.7 22 31
Social activities 36.3 18.7 20
Voluntary & community activities 17.8 9.3 18
Active leisure 16.7 7.4 32
Child care 12.9 9 13
Domestic activities 9.9 5.4 16
Education 4.7 2 22
Personal care 1.5 0.5 16
Passive leisure * * 0.1 22
Total 203

(a) Includes journeys to and from work as well as journeys to look for work.
(b) Components do not add to total because people may undertake journeys for more than one purpose on an average day.

Remarkably little (work, child care, and possibly education - 66 of 203 minutes of driving) is non-discretionary and more or less unavoidable, assuming zero public transport and not able to bike, walk, etc. The rest can be set aside - "passive leisure", driving just for fun - or rearranged for efficiency - shopping can be done weekly all in one go, etc.

Next to how much you use the car, whether you hit the accelerator hard or not, or keep an extra spare tyre in the back, those things are just irrelevant.

For new readers, my long time advice:

ELP Plan (April, 2007)

In this article I will further expound on my reasoning behind the ELP plan, otherwise known as “Cut thy spending and get thee to the non-discretionary side of the economy.”

Why is there two percent columns and what are they referring to? Percent of what? Trips?

Sorry - now I see I can't go back and edit it, there must be a time limit on that.

As you can see from the source for the figures, the first percentage is "proportion of people" and the second "percent of trips taken". The first does not sum to 100% because it's a measure of, of all people who ever sit in that particular car, how many are sitting in for that particular trip. And the second's just, of how trips the car is doing, what percentage is for that trip. The last is the average time spent on that particular kind of trip daily.

The purpose of a journey also affects the time spent on it. In 1992 people spent, on average, 20 minutes per journey. The longest time spent was for active leisure. 7% of journeys were undertaken for active leisure reasons, such as exercise and holiday travel, and these journeys took an average of 32 minutes each. This was followed by journeys for work (31 minutes per journey) and journeys for education and passive leisure, such as travelling to borrow a book or video (22 minutes per journey). Time spent on travel is also related to distance travelled. For example, people are likely to live relatively close to shops, education and child care facilities, but further from work. Therefore, journeys to work take longer than journeys for these purposes.

So in fact in summing to 203 minutes daily I was wrong. The average time spent each day driving is 97 minutes, as you can see from the link.

(you can't edit once there are replies; this keeps you from putting them out of context.)

Great timing Luís!

Yesterday I filled my car with £1.259/litre diesel and set off on a 214 mile journey. I had some time and burning such expensive fuel ($9.44 per US gallon) the challenge was to minimise fuel consumption. I drove very gently, never using more than half throttle, keeping the speed between 50 and 60mph.

It took 4hr 40mins at an average speed of 46mph and I achieved 70.6 miles per UK gallon (58.8 per US gallon) or 4.0l/100km. At the end of the 100 miles motorway section the computer was on 73mpg.

I've done this journey in this car several times in the past and with more conventional driving the car returns around 55mpg. Eco-driving saved me 22%.

The car? A 2004 Skoda Fabia VRS with a 130bhp turbo diesel engine from Volkswagen AG. The car develops 229 ft-lb of torque and accelerates 0-60 in 9.2 sec.

If you had done the trip in 30 miles less time, how much additional money would you have spent on fuel? That's one way to calculate how much you value your time.

If I had averaged 60mph instead of 47mph I think the economy would be around 55mpg. The time saving would have been 1hr 6min (1.1hrs) and it would have used an extra 3.85 litres at a cost of £4.85. So the saving of eco-driving works out at £4.41 per hours. Less than my time is worth... when someone is paying for it, but a pretty good saving all the same.

Luis, thanks for this. In general its good stuff but the mixed message is confusing for me - and I'm sure also for the public at large. Are we aiming to be fuel efficient because we are running out of fuel and it therefore costs a fortune or because we are concerned about CO2?

The Commission's energy policy is an utter shambles because they too are totally confused about this point.

The Commission / National Governments will need to go much further than this. We need lower speed limits on all Europe's roads - and we need that this year. And we need to legislate on automobile efficiency. One way is to legislate on engine size and power - but it is perhaps best to give the engineers some slack and set targets for new car efficiency together with a warning that the targets will be tightened on a rolling basis. So one day in a decade's time we will be driving cars that do 100 mpg - or run on electricity.

I'm also totally bemused by Andris Piebalgs latest blog entry.

We had seen a similar phenomena when the Commission liberalised the sale of gasoline and diesel. Many supermarkets across Europe have entered this market, and this had a positive impact on prices and in the freedom of choice for consumers.

In my neighborhood 4 local gas stations have closed in recent years leaving only 1 left. It has been converted into a shop and doesn't really sell the oil and car accessories you would expect from a well stocked garage. And because its the only one there are always queues. It seems Piebalgs is quite pleased with this outcome whereby it is difficult / impossible to service your car locally but must drive miles to the supermarket, sitting in queues of traffic on congested roads. And this is presented as a positive impact on price and choice.

Jees its no wonder we are in a mess.

I posted this stuff because as Andris says no one has been educated to eco-drive. As you can see from Chris' example above you can really save fuel if you drive intelligently, you need to know your car and a few basic rules, but it is really easy. I can but welcome this initiative.

Of course this campaign has been devised on CO2 emissions, it seems to me that it just coincided with the present high oil prices by chance. De-regulation and unbundling are total nonsense, luckily as we move towards Nuclear in Europe these kinds of "smart-ass" policies will fade away. I wonder if anyone at the Commission sees the total anachronism between unbundling and de-regulation and the promotion of Nuclear energy...

On short term measures to save fuel, beyond the speed reductions (that are very unpopular here) I can see the following:

  • Tax jet fuel and auto-gas (liquefied petroleum gas – LPG).

    There's no logic reason for having these fuels subsidised. Auto-gas even has the disadvantage of promoting the less-efficient Daimler engines. Jet-fuel subsidies are delaying the transition to long distance rail travel. On jet-fuel we could start by taxing only flights inside the EU and then promote agreements with our partners (I tax here, you tax there), first with Russia, then North America, then the Middle East and so on.

  • Harmonize fuel taxes in the EU.

    This is an important issue, we have a big gap from Portugal to Spain, almost 20 cents on diesel, rumours of smuggling are becoming more intense and borderline filling stations in Portugal are going broke. But more than that, we have diesel more expensive than petrol in some states, at the same price in others and cheaper in others still. The EU needs a single equal tax in all states, with VAT making the difference from state to state, that creates a real difference between petrol and diesel (benefiting the later).

  • Diesel independence.

    After decades of tax policies benefiting diesel use over petrol (and rightly so) our politicians just stood there awaiting for new or retrofitted refineries to show up like mushrooms. Well, they didn't. If it is true what our friends from ASPO-USA are saying, that we are living on diesel from the US, we are in for deep trouble this coming fall. We need a programme for diesel independence now.

  • Decommission the road freight transport infrastructure.

    Start working right now on the demise of freight transport by road, it will be much easier than wait for lorries' drivers start blocking the roads. All inter-state freight transport should be diverted either to maritime, fluvial or rail modes, which ever is more useful; at the same time have a programme for recycling and re-integrate lorry drivers on other professions. Maritime trade routes were a founding stone of Europe and shall continue to be so.

In city driving and in congested highway driving, one's "reward" for driving responsibly is that cars cut in front of you to fill any gaps between you and the vehicle in front of you. This is despite the law relating to the number of car lengths between you and the vehicle ahead of you as a function of speed. Enforcing this one law would help considerably in attempts to get better gas mileage.

The best advice, of course, is to stay home and do things like tend your garden.

We also save miles at our house by having all our vegetables delivered. This luxury is actually cheaper, even excluding vehicle costs, than going to the store ourselves. The company delivering these items is talking about branching out and becoming a full service grocery. This will help even further.

In city driving and in congested highway driving, one's "reward" for driving responsibly is that cars cut in front of you to fill any gaps between you and the vehicle in front of you.

In Texas, we just shoot the tires out of cars that do this.

Just (mostly) kidding.

Totally off topic, but what the heck, it's a slow weekend:

In the past, I have related some of my "Texans and their guns" stories. One of my favorites was a guy (in the early Nineties) who witnessed a man shoot and kill a woman, just outside a mall in Fort Worth. Said witness returned to his car and pulled out his 44 Magnum. He then walked up behind the shooter, who had returned to his car and was about to drive away. The witness executed the shooter with single gunshot the head. The grand jury declined to indict the witness/second shooter. No charges were filed.

An eye for an eye...

Sweet! Now THAT is a working criminal justice system!


Andris's heart may be in the right place but the idea that eco-driving will reduce one's consumption by up to 37% beggars belief. Here is what I wrote on his blog:

Carolus Obscurus Says:

May 29th, 2008 at 7:26 pm
Tonyw writes:

it is appalling that the EU has no plans for peak oil. Why is it being avoided?

Because the vast majority of the general public and the politicians they elect still live in a world of fantasy and wishful thinking. A textbook example is Andris’s own account of his experience with an eco-driving simulator (see above). He writes:

By applying all eco-driving tips, a normal driver is able to reduce his energy consumption in an urban circuit from 7.3 l/100km to 5 liters.

Well, yes – but only on one of those simulator thingummies. On the real existing streets of real existing cities the likelihood of any normal driver being able to reduce her fuel consumption by 37% simply by applying a few eco-tips approaches zero. Perhaps amber or red light jumping would help, but that could have nasty consequences.

On a similar vein, Commissioner Wallstrom has recently divulged on her own blog that

… by boiling less water – i.e. only just enough for your cup of tea – you could help save a lot of energy. If all Europeans boiled just the water they needed, thus avoiding 1 litre of unnecessarily boiled water per day, the energy saved could power one third of Europe’s streetlights.

Fairy tales of this kind tempt one to award a prize for the most ridiculous energy-saving tip of the month, something fit for ‘Private Eye’ or ‘The Onion’:

– don’t keep your cat in the fridge overnight. If all Europeans avoided keeping their cats in the fridge overnight, the energy saved could power one trillionth of Europe’s streetlights …

etc., gotta go now and take my piping hot soup out of the deep freeze. Oops.

Now there’s a cool tip for the eco-warriors of Europe.


When will people learn the first fundamental lesson?

The independent variable is the cost of energy, not consumer behaviour. Consumer behaviour is the tail; the cost of energy is the dog.

Then there's the Jevons's paradox. Argument 107 ... won't go thru it all over again

I know, I know, I'm a party pooper. Can't help it. Have read Catton, Georescu-Roegen etc.


I'm a party pooper

Just by chance so am I!

All these silly initiatives such as fitting energy saving lightbulbs are as you imply "painting over the rust".
Quoting figures such as howmany street lights we can power if we switch of the odd appliance or two gives impressive numbers in quantity, but as a percentage of energy use its futile.
I'm not against saving, I do all these things, just to save money.

Near where I live they are putting up traffic lights at junctions on main roads that stop huge amounts of traffic, even when nothing is at the other junction. I don't need to do calculations, I will just speculate this causes an increase in energy use that would power quite a few street lights, and I am only referring to one juction in particular, the A617/A612 junction in Nottinghamshire uk. There are countless poorly phased traffic lights in the uk.

Thanks, partypooper. At least now there are two of us. With four, we could set up a quartet. :-)

Driving less shouldn't be termed as "eco friendly" because you are doing no good for environment, just relatively less damage. The right term is "less eco damagingly" or something like that.


Next you'll be saying carbon offset schemes where Westerners pay for diesel pumps to be taken off Indian subsistence farmers and replaced with treadle pumps isn't actually a useful programme! Madness.

Two weeks ago my wife and I drove round trip from Eugene to San Francisco with a side trip to Sacramento - around 1200 miles total - and averaged 54 mpg in our 1990 Geo Metro. The back was loaded with suitcases and camping gear. We did 55 all the way, usually drafting behind a truck. Having done this trip several times, we noticed more trucks doing 55. Also, instead of taking I5 all the way, we took Hwy 97 from Eugene to Weed, and I5 from there. Hwy 97 has much easier grade and far fewer curves, and had much less traffic.

OK, I guess this is the perfect thread to ask this question.

It is suggested that one not use the A/C because it lowers the gas mileage. That means that one would leave the windows down for airflow instead. This of course lowers the aerodynamic efficiency of the car, but that is a function of speed. So: what is the break-even speed where one should switch from open windows to air conditioning? Obviously, this is different for each car.
I think that the manufacturers should be required to publish this speed. They have done the wind tunnel tests and know the specifications of the A/C compressor, so it shouldn't be that hard for a competent engineer to calculate this number in a couple of hours.

One other thing. I drive a manual Jetta TDI. I can use the high gears at slow speed and the engine will run smoothly as long as I keep the RPMs above about 900. But, when I do this, I have to go almost to full "throttle" if I want to accelerate, or if there is a slight incline.
So, is it better to go fifth gear at full throttle, or fourth gear at 1/3 throttle? (nevermind that throttle isn't the right word because my diesel engine has no throttle plate)
It would really help to have an indicator of how much fuel is being used instantaneously. That way I could actually drive most efficiently. It would also have another benefit; I would get feedback about the throttle condition in cruise control.

Do any VW engineers read this site? That would be convenient.

You can often hear the revs at which the turbo begins working loudly in a turbo diesel, [this applies to Chris Vernons post above too]. Below this the fuel use is very frugal and above this there is marked higher consumption. I noticed this when I had a peugeot TD. So listen for the turbo whistle.

Here are a few points about efficiency:

At idle the efficiency of an ICE is zero (enter hibrids), its a heater, same applies to an electric motor off load.
At full throttle max speed (light load) efficiency approaches zero. The engine's torque is absorbed by losses.
Losses in petrol engine are thermal, friction and from throttling (all end up as heat), diesel engines do not suffer throttling losses. Throttling losses in a petrol engine are zero at maximum torque demand (WOT), throttling losses in a diesel are always zero.
It follows diesel engines have a better part load efficiency than petrol engines, which is by far the predominant factor in the economy gains of diesel. It is a myth it is down to the increased compression ratio.
Increasing the compression ratio from 10:1 ish (typical petrol) to 19:1 (typical DI diesel) takes theoretical efficiency from about 60% to 65%. The frictional losses in a diesel are greater due to larger bearings and higher loads, which absorb some of the thermal efficiency gain.
When there is sufficient exhaust gas flow that the turbo becomes effective, the engine can potentially consume more fuel, but in doing so it will increase the vehicle speed (no hills in sight), so in equilibrium the turbo will make no difference, its the driver's foot that matters. Under normal operating speeds there is insufficient flow in the exhaust gas to "spool up" a turbocharger without the addition of fuel into the engine. This is true even though a diesel passes fresh air in overrun. For those who don't believe this try a pressure guage and see for yourself.

Engine friction (and inertia) as seen by the wheels varies by the square of the gear ratio. This means that in first gear, the engine friction, as seen by the wheels, may appear 16 or more times greater than in top.


Calculating the max fuel economy of a car is a multivariable function, which will be difficult to solve!

Under normal operating speeds there is insufficient flow in the exhaust gas to "spool up" a turbocharger without the addition of fuel into the engine. This is true even though a diesel passes fresh air in overrun.

I have engine-braked down mountains and heard the turbo spinning at a pretty good whine, and max torque on the VW 1.9 TDI is at a rated 1900 RPM.

Not pumping un-needed air is a good thing, because it decreases exhaust backpressure and the consequent engine pumping losses.


VW claim a max torque of 305 Nm at 1750 rpm for their 1.9 tdi. If I said the sky was blue you would argue with me, but its all good fun. I do quite a bit of diagnostic work on engines and can assure you at 1750 rpm without fuel, ie overrun, the boost pressure will not be anywhere near the rated value. at 3000 to 4000 rpm, which is ouside the best operating range for most diesels there is enough air passed to give some boost.
Turbos whine well before they reach the 150000 (or so) rpm. I use a boost guage not my ears to measure boost pressure. Variable vane Turbos obviously improve matters.

Not pumping un-needed air is a good thing, because it decreases exhaust backpressure and the consequent engine pumping losses.

So why don't diesel engine designers shut the air intake at overrun. Partial throttling not only adds to pumping losses it reduces the BMEP of the engine and efficiency with it.

I await your reply with eager anticipation!

VW claim a max torque of 305 Nm at 1750 rpm for their 1.9 tdi.

Must depend on the particular 1.9.  Mine's in a US-spec 2004 Passat; your mileage may vary. ;)

So why don't diesel engine designers shut the air intake at overrun.

Because engine braking is an important safety feature?  If I had a driver-controlled exhaust brake, I'd use it a lot.

Although I can't remember the answer, the A/C vs. window thing has been discussed in the past at - playing around with the search engine there should find the answer for you.

As to instantaneous fuel consumption, if you have a laptop you can buy the software at this page to readout loads of stuff about what your engine is doing (including the fuel consumption I believe). (I have the $100 version with a home made cable, you can buy the whole thing with cable for about $200 if you don't want to make your own).

I've been "eco-driving" ever since 9/11 but I've never referred to it as such and I've never thought "Ohhh look, I'm saving the planet". Mostly I've thought that it keeps a few more bucks in my pocket and out of the treasuries of foreign governments.

This "greenwashing" is getting a bit ridiculous. Conservation is good to save yourself money, but don't try to pretend that you are doing anything more than that. In fact, all we're really doing is subsidizing the people who waste energy by reducing demand.

EDIT: Removed bitter non-constructive overshoot comment :)

Phreephallin writes:

This "greenwashing" is getting a bit ridiculous. Conservation is good to save yourself money, but don't try to pretend that you are doing anything more than that. In fact, all we're really doing is subsidizing the people who waste energy by reducing demand.

Nicely put. It's also called ' cosmeticism' (a term which I think was introduced by Catton in his classic 'Overshoot').

I've used eco-driving techniques for 30 years. Interestingly, they're the same techniques taught in professional driver training courses for Fedex drivers. When I was farming, there was a campaign to encourage farmers to "upshift and throttle down" on light duty field operations. Most of my time in manual transmission cars has been with Chrysler undersquare, long stroke engines: the 225 Slant-Six and 2.5 liter four. These engines will lug all day long without complaint, just like a big tractor diesel. As long as the load is light, upshift and throttle down.

During our big Memorial Day holiday week, I had to drive 2,400 miles cross country to stay with my mother in hospital. Half the miles were on two lane country roads with numerous small towns. I also made three trips to hilly downtown Pittsburgh. In a 2000 Plymouth Voyager minivan with the 2.4 liter engine and 3-speed automatic transmission, I averaged 30 U.S. mpg. My high was 33 mpg driving across Iowa, the low was 27 in Pennsylvania. The EPA rating for this vehicle is 20 city/25 highway. These older EPA ratings were considered optimistic. (My main vehicle is a 1998 Plymouth Neon with 5-speed manual, and 175,000 miles on the odometer. I average 38 mpg in mixed driving and get over 42 mpg on the highway. I should note that I live in a very hilly city, Mankato, Minnesota.)

Unless I'm in heavy traffic, where I maintain speed to go with the flow, I try not to go over 62 mph. That is the speed at which fuel economy starts to drop off the cliff. Driving on Interstate 80 across Illinois, I noticed that I was passed by only two trucks (both Canadian). Nearly all trucks were going 60 mph. Cars were zooming by at 70. Truckers have definitely changed their behavior as a result of high diesel prices.

I think eco-driving should give most people a 20% improvement in fuel economy. If 20% of trip miles are eliminated (plan ahead to combine functions into one trip), then fuel use could be cut by 1/3. That's not shabby and is doable without investing in new infrastructure. Eco-driving should be an integral part of driver training courses and could be encouraged through insurance discounts. (Eco-driving techniques are plan-ahead techniques that also work to reduce chances of accidents.)


That has to be the mother of all oxymorons and coupled with the graphic of the gas gauge with the green leaf it is worthy of the Onion at it's finest!

Spot on -- see above for my reference to The Onion and Private Eye (so I got in there first). Add Le Canard Enchaine for our French readers, Titanik for the Germans, etc

This is truly the stuff that satire is made of.

Eco-driving is like smoking for health or bombing for peace.

It's like yeah - we will still drive 20K miles a year in our SUVs but we are doing it FOR THE PLANET!!
What a hypocrisy.

Not so in my opinion. "Eco-Driving" can improve the efficiency of one of the largest, most expensive and most energy hungry bits of infrastructure we have on the planet by soom 20%, for free, at least in hard currency. I see that any driving isn't particularly "ecological" in an absolute sense but in a relative sense eco-driving is amazing and deserves far more publicity that it currently gets.

To criticise Eco-Driving is to criticise efficiency improvement which is rather foolish from where we find ourselves today.

To criticise Eco-Driving is to criticise efficiency improvement which is rather foolish from where we find ourselves today.

First of all I actually walk and ride my bicycle as much as possible despite the fact that I live in Florida a very unfriendly place for that. Disclaimer, I do own a 2.0L manual 5 speed ICE automobile and have been driving it as little as possible. I have been using the driving techniques mentioned in this post since the last oil crisis back in the 70's when we all drove at 55 mph. Yet I still think my point is valid and I find the term Eco-Driving to be symptomaticof the continuation of the larger problem, which is a societal delusion that the status quo can continue. I don't believe it can an will continue to criticise any effort to pretend that it can.
Ride a bike or Take a Hike

I agree,
"Eco-Driving" is a misleading attention catcher.

Pumping pressure in the tires and coasting to red light has nothing to do with environment choices.
It's just operating equipment efficiently, that's all.

You don't call someone driving a 30mpg civic an environmentalist, just because they don't drive a 14mpg corvette.
(now if they rode a bike...)