Technology Articles
Diesel Power
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Poor diesel engines. By the 1970s and '80s, they had developed a reputation for being noisy, stinky and noxious. Sometimes they would emit clouds of black smoke, and a diesel vehicle, in motion, could look, smell and sound like something that would give everybody on your block cancer.
And although modern diesels are cleaner and more efficient than ever (not to mention smoke-free), gas/electric hybrid cars have denied diesels a chance to capture the public's imagination--at least in the U.S. Around the world, diesels have been reliable money-savers for years.
A typical diesel offers astonishing mileage (a new Volkswagen Jetta TDI diesel sedan gets 38 combined city/highway miles per gallon), and such new vehicles as DaimlerChrysler's diesel Mercedes-Benz E-Class sedan drive just like normal, gasoline cars--but hybrids are the darlings of the moment, because the technology is new and celebrities drive them. As soon as Oprah shows up to the Academy Awards in a diesel, things might change.
The stage is set for the popularity of diesels to increase, especially as hybrids lose their newsworthiness. Consumers are thirsty for fuel-efficient vehicles, and diesels are a major player in the race to build alternatively fueled cars. Americans have as many diesels from which to choose as they do hybrids. In Europe, compact diesel cars are everywhere, and customers can buy diesel versions of such extravagant vehicles as Land Rover's Range Rover SUV from Ford Motor and BMW's 7 Series flagship sedan.
Clean, efficient diesels are mainstream in Europe and rare in America for several reasons that we will explore in this story--but the recent explosion of media attention on hybrids has contributed to Americans' oversight of diesels.
Diesels have been around for a long time and aren't sexy compared with arriviste hybrids. But hybrids, despite all the hype, are not as efficient as people think. Consumers are frequently unable to reproduce hybrid mileage figures obtained by the Environmental Protection Agency, which tests cars in a specific way. Car companies have figured out how to design fuel systems that excel in E.P.A. mileage testing, just as they have figured out how to engineer safety systems that excel in crash tests. For both safety systems and fuel systems, the difference between test results and real-life results can be substantial.
Still, you can fuel your hybrid at any gas station. That's a major advantage. According to the Frederick, Md.-based Diesel Technology Forum (D.T.F.), an organization created by companies working on the technology (including the Big Three, all of whom sell diesels), only 42% of American filling stations sell diesel.
Inventories of diesel cars are also limited. For example, due to regulations that vary in strictness on a state-by-state basis, you cannot buy the diesel versions of the Jetta TDI, Jeep Liberty SUV or Mercedes-Benz E-Class in Maine, Vermont, Massachusetts, New York or California. (If you are interested in buying a diesel, you should call your local dealership to check if it is actually available).
Still, if someone who knew nothing about engines heard of the differences between diesel and gasoline, he or she would think the choice of diesel was a no-brainer and would not understand its scarcity in America.
Diesel is a petroleum-based fuel with a higher energy content than gasoline. In a typical gasoline engine, combustion of the air-fuel mixture occurs by spark, but in a diesel engine combustion occurs by drawing air into the cylinder and compressing it to a high temperature that will burn fuel subsequently injected. According to the D.T.F., diesel's greater energy content, coupled with the efficiency of compression ignition, explains why diesel vehicles get better mileage than gasoline-powered cars.
But diesels are rarely seen in the U.S. for significant reasons. Of the many issues that have stopped diesels from catching on here, we think three stand out:
(1) Perception and Memory. It's hard to forget the awful diesels that were on the road in decades past.
(2) Comparative Government Involvement. European diesel buyers had historically enjoyed tax advantages. In a statement released in 2004, Porsche said, "It was only due to a policy of subsidies that the diesel engine had been able to garner any significant market share in Europe. In the U.S.A. and Japan on the other hand, the market share of the diesel engine was on the order of 1%."
(3) Emission Concerns. Perhaps the most significant reason for diesel's delayed comeback here.
In recent years, major breakthroughs have made diesel much cleaner. For example, new filter technology on modern-day diesel cars traps and burns combustion particles into more acceptable carbon-dioxide gas.
But reducing hazardous diesel emissions has been a slow process that is still going on--and not everybody believes in diesel engines. Porsche chairman Wendelin Wiedeking has been among the most outspoken critics of diesel engines, saying to us in an interview that he believes they are bad for the environment.
In the same Porsche statement referenced above, Wiedeking said, "Due to the deployment of three-way catalytic converter drive units, gasoline engines have unparalleled environmental compatibility. Moreover, we are of the opinion that--in terms of consumption--the gasoline engine has more development potential than the diesel engine."
On the other hand, the D.T.F. states on its Web site that clean-diesel engines emit lower levels of certain emissions compared with gasoline engines ("clean diesel" being a process that combines advancements in diesel engines, cleaner-burning fuels and emissions-control systems).
"Diesel emits only small amounts of carbon monoxide, hydrocarbons and carbon dioxide," writes the D.T.F. "In addition, the fuel efficiency of diesel engines means they burn considerably less fossil fuel."
The slide show that follows contains a list of clean-diesel vehicles now on sale in America. We have also added a list of five cool diesels you can't buy here. Please note that in addition to the vehicles mentioned in the slide show, such full-size vans as Chevrolet's Express from General Motors and Dodge's Sprinter are offered in diesel versions. The source for our lists is the D.T.F.
Despite the limited availability of diesel cars in the U.S., the slide show demonstrates that not only are such vehicles available, but they are available as variants of normal car lines--model series that you see everyday, such as Volkswagen's Golf and Dodge's Ram. Some hybrids, on the other hand, such as the Insight hatchback from Honda Motor, look willfully bizarre.
But, as is the case with hybrids, diesel offerings are few and far between. The slide show will show you what is available, but it might leave you as it leaves us: wondering why diesels are not more popular.
