We recently interviewed Alan Schaeffer, the executive director of the Clean Diesel Technology Forum, a not-for-profit whose mission is "to help people understand the value, and the progress potential, of diesel." We've also heard about ultra-low sulfur diesel and some of its benefits. With the recent announcement that VW will be coming out with a 70 mpg diesel-hybrid Golf, it seems clean diesel has hit the mainstream. However, not everyone is jumping for joy over clean diesel. A recent blog post by Jerry Garrett on the NY Times Wheels blog looks at the pluses and minuses of the technology and finds that, in the end, his "enthusiasm has been damped." See why after the fold.For starters, he notes that many manufacturers, including Mercedes-Benz, Volkswagen, Audi and BMW are on the verge of releasing so-called 50 state compliant diesel vehicles. This means that Americans across the country will be able to benefit from the increased efficiency (25-50% compared to gasoline) and increased torque of diesel, as well as the ability to run the car on biodiesel without any modifications to the engine.
Now for the downsides. Even 50-state compliant diesels "are not capable of getting down to, say, ultra-clean SULEV emissions levels (a certification standard under California’s emissions regulations, which are the toughest to meet)." In other words, whereas diesels are about "20 percent cleaner when it comes to carbon dioxide emissions," they are dirtier when it comes to other emissions such as nitrous oxide. Another issue is that choosing a clean diesel vehicle will add "up to $2,000 to your new car’s window sticker." Of course, given that people seem to be eager to pay a premium for a hybrid, it isn't clear why the added up-front cost for a clean diesel is any different. And just as with hybrids, it can take several years before the fuel savings make up for the higher up-front cost of a diesel (although some studies have found that hybrids can pay for themselves in as little as two years with high gas prices and tax credits).
The author also claims that "diesel fuel isn’t as widely available as gasoline" which, while technically true, is misleading. According to Allan Schaeffer, as of two years ago 42% of all service stations in the U.S. had a diesel pump, and that number keeps increasing. Finally, he argues that diesel fuel is more expensive in the U.S. than gasoline, a claim that is true today, but may not necessarily be true in the future.
The bottom line is that today's diesels are clean, efficient and far quieter than they were 30 and even 5 years ago. For some uses, such as light-duty trucks, their higher torque and efficiency makes them clearly superior to gasoline. For others, the decision is more difficult. Either way, it's essential that we keep our facts straight, and remember that no matter what we drive, we can always find ways to drive less, carpool, take public transit, walk, bike or even commute by kayak!