Clean Diesel vs. Hybrids

Does Clean Diesel Beat Out Hybrids?

Mercedes-Benz, Jeep, and Volkswagen all rolled out new diesel passenger vehicles at the 2004 New York International Automobile Show. Perhaps these car makers are thinking that higher gas prices and advances in diesel technology will convince more Americans to buy diesel vehicles, which currently make up 40 percent of auto sales in Europe.

The manufacturers also might be thinking that diesels will be a fix for meeting ever-stricter federal fuel economy standards. Jason Mark of the Union of Concerned Scientists explains “some of the very features that make diesel engines more fuel efficient are the factors that cause increased air pollution.” Under current emission standards for cars and trucks, diesels are allowed to emit more than twice as much nitrogen oxide as gasoline vehicles and 10 to 100 times more particulate matter.

Diesel Exhaust Causes Cancer

If the particulate matter emitted by diesel engines seems like just another abstract pollutant that may not have real effects on your health, then check out these facts published by the American Lung Association:

  • Diesel exhaust is listed as a known carcinogen under California’s Proposition 65.
  • The extensive scientific literature demonstrates that exposure to diesel exhaust increases the risk of developing lung cancer, and accounts for more than 70 percent of the cancer risk from toxic air contaminants (in California).
  • Diesel is a major contributor to ozone pollution, a powerful respiratory irritant that may lead to shortness of breath, chest pain, wheezing, and coughing.
  • Children are among those most vulnerable to the health risks of diesel exhaust exposure.

Public health researchers are also starting to raise questions about the noncancer risks posed by diesel particulates. Preliminary research suggests that modern diesel engines emit substantially more of the smallest soot particles (ultrafines and nanoparticles) than gasoline vehicles over emission test cycles. The tiniest particles are thought to penetrate deeper into the lungs and pose greater noncancer health risks than the larger particles.

Obstacles to Bringing Clean Diesel to Market

These health risks have led to stricter federal standards for diesel and represent major obstacles to increased reliance on diesels, according to Walter McManus, Executive Director of Global Forecasting at J.D Power and Associates. He explains that consumers may have difficulty finding the low sulphur diesel which U.S. refiners and importers will be required to produce starting in 2006. In addition, the diesels may very well not pass stricter emission standards phasing in over the next few years. McManus concludes that “hybrids are here already and they’ve been here for a while. They have a big advantage over clean diesels in terms of awareness and consideration.”

Dave Hermance concurs. Hermance, Executive Engineer for Environmental Engineering at Toyota, explains “clean diesel is a bit of an oxymoron, because clean diesel is not nearly as clean as gasoline, even in its clean state.” He admits that there will be a growing percentage of clean diesels in markets where the exhaust emission standards are less rigorous, and even applauds their performance. “The new TDI diesels are a hoot to drive. They’re great fun. We may be able to get them as clean as the average car. That’s the hope, but the hybrid technology can be way cleaner—90 percent cleaner than the average new car. So the probability of having clean diesel compete with hybrid vehicles on an absolute emissions basis just isn’t going to happen.”