New generation of diesels coming

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Vehicle manufacturers are turning to century-old diesel technology as a solution to the growing fuel thirst of today's bigger vehicles. Diesels that get as much as 30 percent more miles per gallon than today's gasoline engines have been endorsed by the California Air Resources Board as a viable technology for reducing petroleum use and pollution.

Skyrocketing sales of gas-guzzling pickups, SUVs and minivans in recent years is spurring demand for more fuel-efficient engines that can reduce our soaring dependence on imported petroleum.

In some segments, mostly in heavy- and medium-duty pickups, diesels already have captured half the market. But those big trucks are used mainly by companies and tradesmen who appreciate fuel economy and are willing to put up with the negative aspects of diesel fuel.

Negative factors include higher prices than gasoline in many areas, exhaust smell and the messiness associated with refueling. Some people will not handle a diesel hose without gloves. But diesels don't have to be that way. I have recently been driving a European version of a diesel-powered Mercedes-Benz E320 that will go on sale in the United States next March.

Externally, there's nothing about the Mercedes-Benz that tips you off to its inline six-cylinder diesel engine. There's no diesel smell inside or immediately outside the car. Turn the ignition key and the engine kicks over instantly. Even though the engine still has glow plugs, there's no longer any warmup required. Nor does the engine sound like diesels of old. In addition, the car has plenty of power.

In Germany where there are no speed limits on certain superhighway Autobahns, the 200-horsepower car can be driven at speeds of more than 100 mph easily. But that's not where you get the most advantage out of a diesel. Stop-and-go city driving is where diesels are most efficient.

The engine is ideal for the way most Americans and Europeans drive -- a mixture of city and suburban driving.

That's why 42 percent of Mercedes-Benz sales in Europe are equipped with diesels. In Italy, about 90 percent of Mercedes-Benz are purchased with diesels. Mercedes-Benz diesel sales targets in the United States are much more modest than that.

It expects to sell 3,000 to 3,500 diesel E320s out of a total of more than 200,000 units it sells here annually. Pricing hasn't been set yet, but a Mercedes-Benz spokesman says the diesel model could be priced less than the gasoline version.

Volkswagen has been the diesel leader in the United States. Its TDI engine, a turbocharged, direct-injected diesel, has been popular in Golf and Jetta models, despite the fact that you must pay a premium for the engine. The TDI is delightful to drive. It's powerful and gets 45 miles per gallon without the negative things associated with diesels.

VW will introduce an all-new, V-10 diesel next spring to power the new Touareg SUV. It will be priced at $53,000, compared to the $48,000 for a V-8 Touareg. The V-10 is said to provide 20 percent better fuel economy and 83 percent more torque -- a great asset for towing and climbing over boulders.

Chrysler sells the diesel-powered Voyager and PT Cruiser, as well as the Jeep Cherokee and Grand Cherokee in Europe. The company is planning to introduce a diesel Jeep Liberty here late next year.

GM is working on a new diesel for its SUVs, says Tom Stephens, powertrain czar for the world's biggest auto company. He says that GM also is working with alliance partner Fiat -- a leader in diesel engine design -- on new powerplants for light vehicles.

There's a sense of urgency throughout the auto industry to perfect diesels. The EPA has decreed that SUVs, minivans and pickups must be more fuel efficient and cleaner burning by 2007. Corporate Average Fuel Economy for these types of vehicles currently is only 20.7 miles per gallon. The new mandate will require a CAFE of 22.2 miles per gallon for vehicles in that segment by 2007.

Vehiclemakers won't be able to achieve those higher fuel economies with fuel cells or other advanced technologies. Hybrids are being readied, but these vehicles have the disadvantage of being expensive and complicated. Diesels are a mature technology and can achieve about the same increases in fuel economy as hybrids, but engine manufacturers need to get them to burn cleaner.