The Volkswagen Jetta uses a "clean diesel" engine that is more powerful and fuel-efficient. (Volkswagen)
Dirty and loud, smelly and unreliable: That's how many Americans remember diesel-powered cars from the 1970s, when oil shortages prompted automakers to produce a bevy of the more fuel-efficient vehicles.
The bad rap that diesel engines received caused them to virtually disappear from the U.S. car market by 1980, aside from some trucks and Volkswagen models. That, however, may be about to change.
What is clean diesel?
- Diesel engines produce 10 to 20 percent less of the greenhouse gas CO2 than gas engines do, but until recently the high sulfur content caused them to spew far more soot and other particulates, as well as nitrous oxide.
- Since 2006, a more refined, ultra-low-sulfur diesel engine has been available across the U.S. This reduction has allowed auto manufacturers to create clean-diesel engines and exhaust systems that can filter out most of the particulates.
"There's a night-and-day difference in emissions, power and smoothness between this Jetta and your 2002," Volkswagen salesman Leighton Russell said, comparing the 2009 "clean diesel" model to my wife's 2002 Jetta TDI diesel station wagon, which sends a cloud of gray smoke up from the tailpipe whenever she starts it.
At the Carter Volkswagen dealership in Seattle, I stood behind a car as Russell started up its cold engine. Not only was there no detectable smoke, but also there was no smell. Seeing, and smelling, is believing.
Rising fuel prices, concerns about global warming and the desire to achieve more energy independence have renewed interest in diesel cars in the U.S. On average, fuel economy is 20 to 40 percent better than with a comparable gasoline engine.
Automakers, seeing potential to reignite U.S. interest in diesel automobiles, are busy bringing in new models from overseas, where diesels have remained popular. The first to arrive are from Volkswagen, Audi and Mercedes-Benz.
Ownership costs
- Because diesel engines are more expensive to produce, those models traditionally carry a premium of a few thousand dollars.
- When the U.S. began the change to ultra-low-sulfur diesel fuel and the cost of diesel fuel jumped, it became tougher for drivers to recoup the upfront cost. But retail diesel fuel prices have dropped in recent months; it now costs about the same as premium gasoline.
- In addition, buyers of some diesel vehicles may be eligible for federal tax credits, and a recent study by IntelliChoice.com found that clean-diesel vehicles deliver a lower cost of ownership compared to their gasoline-burning counterparts.
- --Associated Press
At the New York auto show in April, Mercedes debuted its GL350 BlueTEC diesel SUV and Audi displayed its Q7 diesel SUV, which gets 27 mpg on the highway with a V-6 engine that gets more power than a gasoline V-8, according to the company.
Several other manufacturers, including Honda, Toyota and Nissan, are also considering bringing diesel-powered cars to the U.S.
Diesel fuel contains more energy than gasoline, so each gallon can do more work, and the engines run cooler and at a lower RPM. In Europe and Asia, 34 of the 38 vehicles that got 50 mpg or better used clean-diesel technology, according to a 2007 study by the Civil Society Institute.
The 2009 Jetta that I looked at comes in both gasoline and diesel versions, with the diesel model rated at 40 mpg highway versus the gas version's 29 mpg. Opting for the diesel model would save a driver about $321 annually on fuel costs, use nearly two fewer barrels of oil and result in the emission of one less ton of greenhouse gases each year, according to the EPA.
"You can't tell the difference between these new clean-diesel cars and the gas versions," says Russell. "They're just as quiet. No vibrations. Maybe in acceleration; you step on the pedal of the diesel and it just takes off."
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