The vast majority of Americans are satisfied with cars and sport-utility vehicles powered by gasoline. In contrast to <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Europe, where diesel car sales are skyrocketing, Americans have shown little interest. But that may start to change. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
The biggest plus for diesel cars is fuel economy, which can be as much as 30 percent higher than comparably sized gasoline models. Since this advantage increases with vehicle weight, the fuel economy benefits for diesel SUVs, pickups, and minivans are even greater.
The potential efficiency advantage is nearly as much as one would get by switching to a gasoline-electric hybrid vehicle—an alternative that is slowly gaining acceptance—but with less sticker shock.
Beyond the obvious consumer benefits of less frequent fill-ups, there are policy arguments favoring improved mileage. Some believe more efficient vehicles can help cut dependence on foreign oil and fight global warming (the less fuel consumed, the lower the emissions of the greenhouse gas carbon dioxide). The merits of these arguments are debatable, but those individuals and governments that do believe them should prefer diesel to gasoline.
In Europe, high motor fuel taxes and other policies designed to reduce both fuel consumption and greenhouse gas emissions are a big part of the reason diesel cars are rapidly gaining market share.
"Diesels are approaching 50 percent market penetration in Europe," Gary Smyth of General Motors noted at a recent Washington conference held by the Diesel Technology Forum, an industry coalition.
But in this country, diesels have yet to crack 1 percent of the passenger vehicle market. Other than Volkswagens, few passenger cars are even available in diesel.
One reason is that diesels have a reputation for being dirty, a reputation that is not entirely unearned. Compared with gasoline cars, diesels emit more nitrogen oxides, a contributor to smog, and particulate matter (soot), which the Environmental Protection Agency considers a health threat.
But that will have to change when tough new EPA vehicle standards take effect beginning with the 2004 model year. These standards demand sharp reductions in the emissions of these pollutants and apply equally to gasoline and diesel powered vehicles. In other words, regulators aren’t going to cut diesels any slack for their superior mileage.
Nonetheless, technological advances have reduced diesel emissions enough that at least some manufacturers plan to introduce 2004-compliant diesel versions of popular models, including DaimlerChrysler’s Jeep Liberty and the Mercedes E-Class sedan.
Still, there are lingering doubts about meeting EPA’s requirements, especially when they tighten again in 2007. In addition, there is always the possibility that the next round of standards will be even tougher on diesels.
Regulatory uncertainty is one reason several carmakers have hesitated to make big long-term investments in American diesels.
Diesels also have a perception problem that may prove a tougher challenge than the regulatory burden. Earlier attempts at diesel cars in the 1970s and 1980s had problems with noise, vibration and odors, leaving American consumers with a bad impression.
In addition, the big declines in diesel emissions are relatively new and have not yet changed the environmental image of diesel in America. We’ve all had the experience of being stuck in traffic behind an old diesel truck belching thick black smelly exhaust. It will take time for the public to realize that diesel has moved well beyond that level of technology, and longer still before environmentalists even consider embracing diesels in the way they have embraced gasoline-electric hybrids and other alternatives.
"Eventually, the perception will catch up with the reality of clean diesel, which is why I’m optimistic," says Allen Schaeffer, Executive Director of the Diesel Technology Forum.
Today’s diesels may never take off here as in Europe, but their benefits may help them break out of their status as a fringe player in passenger vehicles.