5 clean diesels: The future is now

Today's diesel cars are clean, quick, quiet, odorless and get great fuel mileage. Since they don't smoke or clatter, you won't know you've encountered one.

Here's what makes clean diesels possible: ultra-low-sulfur diesel fuel, which eliminates diesel stink and allows a series of exhaust-scrubbing devices. First to clean the exhaust is an oxidation catalyst that removes unburned hydrocarbons. A soot and particulate filter eliminates diesel smoke. In some, a chemical is injected that changes smog-producing nitric oxides (NOX) into ammonia. A second catalyst turns the ammonia into harmless nitrogen and water.

Compared to gasoline, diesel carries more energy and, thus, offers more miles per gallon and produces less greenhouse gas. Even cleaner is biodiesel, which is made from vegetable oil.

Here are some cars that will change your mind about diesels.