New emissions rules recently approved by the Colorado Air Quality Commission will treat many of the new “clean diesel” cars and light trucks the same as their less fuel-efficient gasoline cousins. That’s good news for thrifty drivers and the environment alike.
The new rules will go into effect July 1. They will exempt 2004 or newer models of light-duty diesels from emissions testing requirements for four years. After that time, the newer diesel cars and pickups will only need to be tested once every two years, instead of annually.
The new rules simply treat clean-diesel vehicles the same as newer gasoline-powered cars and heavy-duty diesels with gross vehicle weights (the vehicle plus its maximum load) above 14,000 pounds. Such vehicles are already exempt from testing for first four years, followed by biennial testing until they are 10 years old, after which they are subject to annual emissions tests.
The new emissions rules are important because other new regulations requiring ultra-low sulphur diesel fuels, which went into effect Oct. 15, are expected to boost the popularity of the high-torque, high-mileage engines in the United States.
Diesel vehicles are already popular in Europe, where high taxes have long kept motor fuel costs above $5 a gallon. But until now, diesels have had trouble meeting U.S. emissions requirements, especially in California. The new regulations slashed the allowable sulfur content in diesel fuel by 97 percent, from 500 parts per million to 15 parts per million, opening the way to sales of more advanced diesel vehicles.
Diesels cars and trucks get 20 to 40 percent better fuel economy than their gasoline counterparts. The Mercedes E320 diesel sedan, for instance, posts EPA mileage ratings of 26 mph in the city and 37 on the highway. The comparable gasoline-powered E350 has ratings of 19 mpg city and 26 highway.
Both Volkswagen and DaimlerChrysler unveiled new diesel vehicles at the Greater Los Angeles Auto Show last month that already meet the California emissions standards, the nation’s strictest. General Motors and Honda are also reportedly preparing advanced clean diesel units for the U.S. market.
With diesel mileage already rivaling that of many gasoline-electric hybrids, GM is now developing a diesel-electric hybrid that will push the fuel-miser envelope still further. That’s not only good news for American pocketbooks but for the environment as well, since better vehicle mileage translates into less carbon dioxide released into the environment.
