Cleaner, quieter diesels offer high fuel efficiency

With average gasoline prices nationwide inching closer to the $3 per gallon mark -- and already past that mark in some places -- savvy new-car buyers may well ask themselves once more, "what fuel-efficient alternatives are out there?"

While gas-electric hybrids have received a lot of attention, what may loom larger in our automotive landscape in coming years are diesel-powered cars.

Diesels are wildly popular elsewhere in the world -- they account for about 50 percent of all new cars in Europe -- but they have never really stirred the souls of U.S. buyers.

Including trucks, diesels account for less than 2 percent of the U.S. new-vehicle fleet, despite fuel mileage levels that can run 40 percent higher than a comparable gasoline-powered vehicle.

When most Americans think of diesels, the words that come to mind include slow, noisy and soot-belching. Those who remember the horrible efforts by General Motors to sell diesel-powered sedans in the 1980s may also associate diesels with major repair issues.

That could change with the arrival of a new generation of diesels that are cleaner, quieter and more powerful than previous efforts. A drive in the 2007 Mercedes-Benz E320 Bluetec diesel sedan shows this new technology delivers a seamless luxury sedan experience along with a 37 mpg federal rating.

For now, the Bluetec is available in 45 states, since it doesn't meet the more-stringent emission standards for California, New York, Massachusetts, Maine and Vermont. But starting with 2008 models, Mercedes-Benz will add a new injection system that will make the three-liter diesel engine legal in all 50 states.

The Bluetec engine will be transplanted into a Jeep Grand Cherokee model, and Mercedes-Benz plans to expand the diesel technology to other Benz models, including an upcoming entry-level C-Class sedan.

Volkswagen, Audi and BMW also are planning on licensing the Bluetec technology for some of their U.S.-bound 2008 models.

U.S.-based manufacturers so far have not announced plans for diesel sedans, though DaimlerChrysler's Chrysler division is planning a diesel version of its minivan.

Most Japan-based manufacturers offer diesel versions of their sedans in other markets, but so far have shown interest only in bringing diesel trucks to the U.S. market.

Aside from the increased fuel economy, diesel vehicles carry a price premium of about $1,000 to $2,000, which is far less than the premium on most gas-electric hybrids.

Add in the greater durability of a diesel engine compared to a gasoline engine -- 200,000 miles between major overhauls are not uncommon with diesels -- and it could make economic sense to give a diesel a spin.