Alternative Fuels Glossary

Alternative fuels have earned plenty of publicity lately. Even so, most unconventional fuel sources and powertrains are in a state of infancy.

Diesel
Essentially fuel oil, diesel has been popular in Europe for decades, but limited mainly to trucks in America. Only Volkswagen and Mercedes-Benz currently offer diesel-powered automobiles.


Modern direct ignition and other control technologies help eliminate the engine knocking and visible exhaust soot that plagued earlier diesel engines.


Diesel is "highly efficient," said Ron Cogan, editor/publisher of Green Car Journal, yielding 30 percent more mileage and 30 percent less greenhouse gases. In California and four northeastern states, diesels don't meet current emissions standards.

"Clean" Diesel
New federal standards for diesel-powered vehicles become effective in 2007. No vehicles meet them now, though Cogan notes that Volkswagen does "expect to meet the standards." By October 2006, cleaner (low-sulphur) diesel fuel is supposed to be on the market.