The universe of available green cars has expanded thanks to new clean diesel technology. Compared with a similar-sized gasoline engine, a diesel engine delivers about 30 percent better fuel economy, which also means roughly 30 percent less carbon dioxide emissions.
PHOTO: RAFA IRUSTA/FOTOLIA
The 2010 Volkswagen Golf TDI hatchback, formerly the Rabbit, has room for five and is rated at 30 mpg in city driving and 42 mpg on the highway.
Shown above is Audi’s clean diesel engine and ultra-low emissions system, which is a good example of how all clean diesel systems operate. Diesel exhaust is first treated by an oxidation catalyst to convert carbon monoxide and unburned hydrocarbons into carbon dioxide and water vapor. A particulate filter then traps and burns off polluting particulate matter. Some systems also use urea injection to create ammonia for a reaction (in the final catalyst) that removes nitrogen oxide. The final result is a car that meets strict emissions standards.
Fuel-efficient driving team Helen and John Taylor drove a 2009 Volkswagen Jetta TDI 9,419 miles on only 12 fill-ups.
The diesel version of the 2010 GMC Sierra 2500HD has a 40 percent higher maximum torque rating than the gasoline equivalent of the truck.