Audi Diesel wins LeMans, changes perceptions?

The winner: No.8 Audi Sport Team Joest R10. Photo: Bertrand COUSSEAUWhy are diesels currently less than 1% of the vehicles sold in the US and about 40% of the vehicles sold in the EU? One oft-cited reason is the horrible memories we all have of choking as the neighborhood diesel noisily and slowly clanked by.

All that may be changing. This weekend, the Audi A10 became the first diesel powered car to win the 24hr LeMans race. With a particulate filter installed, mind you.

Events like this may serve as a watershed moment for the engine design. When your Audi brochure arrives with a checkered flag and champagne on the cover, you may forget that old Mercedes that just wouldn’t die.

And that could be a good thing for the environment, with the usual positives and negative impacts. Diesel does contain more energy than gas, so mileage is higher, especially where the engine’s high torque is useful. Although burning the fuel emits 14% more CO2 per gallon, the 30% increase in fuel economy means switching to diesel can drop your carbon footprint at least 10%. Of course the drawbacks for diesel are numerous, including a lot of ancillary air quality issues. Diesel has emissions issues: higher NOx and particulate matter are the main problems to be solved.

Perhaps even more exciting is the push this could mean for biofuels, something widely considered as one of the stabilization wedges of climate change. As a biofuel, biodiesel has a higher net energy balance than ethanol and is much closer to economical production today. Its drawback is of course the low number of passenger vehicles capable of burning it. Changing perceptions could mean more enthusiasm for biodiesel among mainstream consumers.

A challenge for the LeMans teams for next year — win it on B100!

UPDATE: Jeff correctly points out that diesels are high-torque not low-torque. Hence usefulness is trucking, etc. Obviously, our esteemed editor is away in Europe drinking Chianti.

Author Bio


Comments Disabled

  1. Jeff Curtis - June 21, 2006

    There are several negative inaccuracies in this post about diesels that I believe should be corrected.
    It is true that diesel fuel has more energy content per gallon than gasoline and this is part of the reason that diesel vehicles get better fuel milage. The other reason is that diesel engines are more efficient than gasoline engines. It is not just the fuel type but also the engine process that yields a 20 to 40% increase in fuel economy.
    Diesel motors have high torque, not low torque, for the equavalent motor size. Torque is what provides acceleration. Modern diesel cars are just as peppy as their gasoline counterparts and get much better fuel milage. An easy side by side comparison can be made with a VW Golf ( The 1.9l TDI diesel gets EPA 46mpg highway, 100hp, and 177lbs-ft torque. The 2.0l gasser gets EPA 31mpg highway, 115hp, and 122lbs-ft torque.
    The author states that the drawbacks of diesels are numerous. While this may have been true 30 years ago this is completely untrue of modern diesel engines.
    The author only lists emissions problems with diesels. Many of the emissions of diesel engines of even 30 years ago are less than the emissions of equivalent gas vehiles. The emissions that have been worse are particulates (soot), SOx, and NOx. Improved engine design, modern electronic controls (similar to gas engines), and in some cases the addition of particulate filters has eliminated the soot from diesel exhaust. Modern diesels don’t smoke anymore.
    The SOx emissions have been due to the sulfer in diesel fuel. The sulfer has been removed from gasoline for years. In the fall of 2006 Ultra Low Sulfer Diesel will finally be available from fuel refineries. This will dramaticly reduce SOx emissions. Europe has had USLD for years now and biodiesel has no sulfer so burning biodiesel produces no SOx.
    Modern engine controls like EGR have already reduced NOx to the current acceptable levels.
    The sulfer in diesel fuel has also prevented diesel engines from taking advantage of catalytic converter technologies similar to gassers because the sulfer “poisions” the catalyst in a similar way that lead in gasoline plugged those catalytic converters. Removing the sulfer will enable the use of catalytic converters to reduce the NOx emissions to the emissions levels acceptable in the near future.
    While the author did not state the other “numerous” drawbacks of diesels I suspect he was thinking of the problems new diesel owners experienced in the last gas crisis. Diesel cars then were slow, noisey, smelly, smokey, they had cold start problems, had to be plugged in during winter and some manufacturers produced unreliable products.
    Modern diesel cars are not your father’s Oldsmobile diesel. Removing sulfer has removed the smell, and modern engine controls have made the diesel quiet and fast and eliminated the smoke and cold start problems. To quote another ad “we have come a long way baby.”
    There are many benefits to diesel ownership and high fuel milage is just the start. Diesel engines last much longer than gasoline engines. Diesel owners regularly get 300k to 400k miles before needing an engine rebuild. Diesel engines need less frequent maintainance and the maintainance is less costly. Oil, oil filter, fuel filter, and air filter are pretty much it. The rest of the car maintainance is the same as a gasser.
    Several recent auto enthusiast magazines have performed side by side comparisons of hybrid vehicles, VW TDI diesels and “normal” gas vehicles. They have had glowing praise for the diesels as fun to drive and having impressive fuel economy, usually surpassing the EPA numbers. The hybrids have tended to be a dissappointment, not living up to the hype.
    Yes, everyone remembers the poor quality diesel products and that is unfortunate because it has prevented American auto manufacturers from investing in diesel engine development. Fortunately our European neighbors have always seen the benefit of diesels (in part to much higher fuel costs) so they have continued to develop diesel engine technology. In addition Europe has lead the development of biodiesel. Biodiesel polutes even less than petrol diesel ( and others) and the majority (85%) of the CO2 comes from biomass so it is renewable.
    Diesel engines and biodiesel fuel are not magic bullets but they are more efficient, less carbon producing, they work and they are available now.
    Before you buy your next car consider test driving a diesel. Many a recent new diesel owner claims they will never go back to gas.

  2. tom - June 21, 2006


    Thanks for your comments. I stand corrected on the torque issue, and as usual, blame it on lack of sleep.

    As for your other points, I mainly agree. Thats why this win is exciting for diesels because it may change the biggest barrier to adoption (in my mind) which is consumer perception.

  3. Anonymous - June 21, 2006

    I am curious with all the talk about diesel engines why I never hear anything about combining diesel technology with electric to make a diesel hybrid. Are there some technology issues as compared to a gas engine?

  4. Tom - June 21, 2006

    There is quite some excitement about diesel hybrids, but they are still a long way from production.

    Peugot may be the closest — check out this 69mpg diesel hybrid.

  5. A completely different Jeff - June 21, 2006

    With the low demand for diesel engines in North America, the current market for a diesel hybrid is almost infinitessimal. The few ‘early adopters’ that might show an interest probably overlap quite a bit with TerraPass purchasers. It’s these early adopters that would have to try to counteract the US perception of diesel sedans, which is still based on the early-80’s models that refuse to die.

    Even Ford is tinkering with a d/hybrid, with it’s Reflex concept at this past year’s NAIAS ( They’re also looking to add a hybrid system to their existing large/work trucks, to allow the same hauling performance with less fuel used.

    The best way to generate buzz for this would be to badger your local auto dealers. If they perceive enough interest in a d/hybrid offering, they’ll pass that on to the manufacturers.

  6. Karl Frederick - June 21, 2006

    Jeff Curtis had several enlightening observations about diesels . . . thanks. I’d like to add a comment about the torque vs. horsepower question that often comes up in discussion of acceleration. Although it is true that torque accelerates the vehicle, it’s the rate of torque delivery (in terms of foot-pounds per minute, for example) that determines the potential for acceleration at any point in time. And that rate is conventionally referred to as . . . you guessed it . . . horsepower. And the whole drive train between the crankshaft and the asphalt determines the delivery of that power.

    A vehicle with a perfect Continuously Variable Transmission (CVT) could theoretically keep its engine at the best RPM for peak horsepower during a maximum acceleration run and accelerate as fast as another vehicle having similar peak horsepower but higher peak torque.

    Engines are generally more efficient at lower RPM, and the CVT also works to optimize engine RPM for economy during level cruising.

    By the way, there’s a good article on the subject here:

  7. Michael - June 21, 2006

    On the fuel side, it should be noted that the LeMans-winning Audi diesel was running on Shell GTL blend of diesel with no sulfur, no aromatics, high cetane and less particulates/NOx/Hydrocarbons than conventional petrodiesel (all good stuff for the environment and fun driving). The fuel is currently available in Europe. So the diesel’s increased fuel efficiency (using less fuel than gasoline) is multiplied by using even less petrodiesel.

  8. Joel Gagnon - June 22, 2006

    One of the reasons so few diesels are sold in the US is that there are so few available to buy. I recently read that VW is ending sales of the Golf in the US due to tightened emissions standards. They are already unavailable in some states, like this one (NY).
    Diesel-electrics have been around for a long time. The railroads used them from the get-go when they switched from steam locomotives.
    Joel Gagnon

  9. Eric - June 22, 2006

    As a motorsports fan, I can tell you that environmental issues and alternative fuels are a big buzz in racing right now. The Indy Racing League Indycar Series is currently running on 10% ethanol and will be running pure ethanol next year. I’d like to see TerraPass do a story on their efforts.

  10. Allan Tweddle - June 22, 2006

    I believe FedEx has a fleet of experimental diesel powered hybrid delivery vans on the roads of San Francisco and Washington D.C. for about a year now. They are based upon a Peterbuilt chassis, with a Mercedes Benz diesel and a hybrid system integrated by Eaton.

    Diesels work even better, are more powerful and much, much cleaner when they run on compressed natural gas. Truckers love CNG.
    But CNG is not available everywhere as it started to be just a few years ago. And CNG’s comparative price per gallon to gasoline currently in California is under $2.00 per gallon.

    And that’s buying it at a gas station. Using your CNG from your home gas supply would be even cheaper.

    When you open up an engine that has been running on CNG at 100,00 or 200,000 miles, you find an engine that is much cleaner, has less wear, (pistons, rings, valves) and in better shape than if it had been running on diesel fuel.

    But CNG has been politically killed in many jurisdictions. One should ask, in this election year, WHY?

    Here in West Virginia, folks who own a home on land that has a natural gas well under lease get their gas free, so some are buying Fuelmaker CNG filler systems, and are fueling their diesel cars over night, and drive free of fuel costs.

    Honda just bought 49% of Canada’s Fuelmaker, and is bringing a line of dual fuel gasoline/CNG cars to market.

    Imagine what we all could do with a diesel car fueled at home with CNG?

  11. Veektor - June 23, 2006

    -It’s great that a diesel won that race!
    -Just so people don’t again get disappointed with the diesel engine, which is a wonderful idea… we had one of those Mercedes which just wouldn’t quit (actually it lasted 200,000+ miles). It was, alas, attached to one mighty expensive car to repair (and it needed frequent non-engine repairs). The engine, and for that matter the fuel, are only one part of the expense equation for the car. Diesels are only available now in the Mercedes and VW cars. Both makes are fine comfortable cars and are probably more fun to drive than the hybrids,but VW and Mercedes are considered less-than-very-reliable by most consumer agencies (and by at least one of the marque magazines), and they are considered very expensive to fix and maintain by every mechanic I have spoken with. We did not raise an eyebrow when we received bills for around $1000 (although parts were indeed available which may explain why they have a reputation for durability). ANyway, if you are primarily (or secondarily) thinking of economy you may want to stick with the hybrids for now. If you do go with one of the currently available diesel cars, please consider the extended warranty.

  12. Cass - June 28, 2006

    Electric motors have the best torque so the diesel hybrid aces out the pure gas or diesel cars. Diesels are also easier to convert to CNG: in California the hybrid Honda Civic, I believe, has gizmo you lease that puts CNG into the car from your home gas outlet.
    In the end the hybrid car is a mobile power plant masquerading as a car, and the cheapest power source in terms of $/kw and kwh/$.

  13. Anonymous - July 6, 2006

    I wonder why its taken so long for the US to mandate low sulfur Diesel fuel, had it been available sooner I’m sure we’d be seeing many more modern diesel powered cars on the road today. The new TDI engines are quiet, smoke free, fast and smell sweet compared to the old dirty toilets spewing black smoke doing 0 to 60 in 24 seconds. I drove a 3.0 TDI Audi in Germany last year and was blown away with every aspect of it. I could pull away from a stop in any gear and that low end was wonderful. I would have no trouble living with that engine here in the USA and give up nothing, if not gaining in much more than fuel savings alone. I look forward to the Diesels knowing first hand how wonderful they preform!

  14. dogboy - October 25, 2006

    Here is a totally new thread; I’m a hotrod builder (translation: American pre war rods) and have a new project that I would like to explore the use of a high torque diesel production engine available in the USA. The project is a 32 Ford roadster, with a home built frame and wood / glass body so it’s really light. I would ultimately like to run this machine on biodiesel. Suggestions?

  15. Tachyon - December 23, 2006

    Great article. I’m glad to see articles that help remove the mostly incorrect perception that diesels are slow, noisy, dirty, expensive and polluting.

    Today’s modern diesels are amazing technology and, in my opinion, have more to offer, and more room for technological advancement than gasoline or ethanol powered ICE engines.

    It’s always been strange to me that diesels aren’t more popular in the US market. They provide exactly the kind of off the line torque grunt that Americans like in a vehicle. Not to mention stump pulling power and great fuel economy.

    Now that we finally are getting decent quality, low sulphur diesel fuel, I hope that manufacturers will start making some great diesel powered family cars, trucks and even sports cars.

    For anyone that doesn’t believe that diesel is ready for those jobs, I tell you to find a Mercedes dealer and test drive an E320 CDI. It’ll change your whole outlook on diesel.

    Now to get the government to promote more use of biodiesel, and B50 in pumps in summer and B20 or B10 in winter and we’ll greatly reduce dependence on foreign oil too.


  16. europe based - January 11, 2007

    We have been driving a diesel Audi A6 wagon for nearly 10 years while living in Europe. It has been an exceptional car, for its amazing fuel economy (about 55 mpg), excellent build quality (only 1 minor repair since 1998), power and comfort. Having driven only gas cars before, we’re completely sold on diesels. Friends who own BMW, Mercedes and VW diesels also think they are great cars to own and drive. Advances in fuel technology should continue to improve their environmental footprint. We hope that US drivers demand high performance, environmentally friendly diesel technology now, not in 5 or 10 years.

  17. Coder - January 17, 2007

    I have a VW Jetta TDI. I love it! I am averaging 49 mpg between highway and city driving. The car has great pick up, quiet and barely any diesel smell. I was able to get my car before VW stops selling them in 2007 in the US. They should be back in 2008.
    America as a whole needs to be more aware of the new diesels and request/demand more of them. If we want them, car manufacturers will get them to us. Its about demand of the consumer that makes companies do what needs to be done. To the manufacturer, its about “keeping the customer happy”.
    I live in a colder climate and during the warmer months run on biodiesel of B50 to B100. While B100 is not available everywhere, it is possible to obtain.

  18. John Stencel - January 19, 2007

    I have a Jetta TDI 1.9, 2006. I have 23,300 miles on it and it is fun to drive. It gets 44+ miles per gallon at higher than Xway speeds. The speedometer is
    about 4% higher than actual in the 80 to 90 speed range. So the actual MPG will also be off that much. But that’s still great mileage. With gas at $3.00 per gallon, 40 miles P/G and an SUV that I have at 15 MPG,
    I will save $21,000 in fuel at 100,000 miles of use.

  19. John - January 20, 2007

    I remember reading somewhere that another factor that really hurt the GM diesels of yesteryear was the fact that there were problems with the supply of diesel fuel in the NE during the winter and some fuel got diverted from the south that had very low cetane value. The engine was of poor design anyway, but having poor fuel made it much worse….

  20. Anonymous - May 8, 2007

    Yosemite’s shuttle buses have been diesel hybrids since 2005.

  21. Steve - June 12, 2008

    We bought a VW Jetta TDI 2 yrs ago. 60mpg makes up about 1/2 the car payment in fuel savings alone.
    More recently we took a trip across country and wanted to find biodiesel fuel stops along the way.
    The sad truth was that out of 30 or so listed bio-fuel “outposts”, 99% of them were for US Govt. ONLY!
    So, be informed. Our govt. is already on bio diesel, we are actually being played by big business.
    Your diesel vehicle will run many types of fuel compared to anything running other fuel types.
    All you need do is some preparation and remain informed.