Detroit's Diesel

New Olds saves fuel--but...

To most Americans, the diesel engine calls to mind a smoke-belching locomotive or 20-ton truck. But in Europe, diesels also power some Mercedes sedans and Peugeots--and this week those cars will get a U.S. rival. General Motors will bring out the first U.S.-made diesel passenger car. It plans to offer the diesel as an optional engine on 50,000 Oldsmobile 88s and 98s in the 1978 model-year.

Detroit engineers long shunned diesels for cars because of their comparatively sluggish performance, noise and weight. But the energy crisis that started with the Arab oil embargo of 1973 caused GM designers to take another look. The diesel gets anywhere from 15% to 25% more miles per gal. than a gasoline-powered engine. Besides that, diesel fuel, which is essentially highly refined fuel oil, can cost as much as 10-c- per gal. less at the pump than regular gasoline depending on the area of the country. And the diesel engine, which has no spark plugs or distributor points, requires less frequent maintenance and repair.

Three years of development have enabled Olds engineers to solve some other problems. A passenger who did not happen to notice the word diesel on the hood ornament or the rear of the car probably could not tell, from quietness or smoothness of ride, that he was traveling in an unconventional auto. Yet some difficulties remain. The most serious is getting the engine to start on a cold morning. Since the whole principle of diesel ignition is to raise the temperature of the fuel mixture by compressing it into a superdense mass in the cylinder, a cold engine block can keep the motor from starting at all. The Olds diesel has a block heater and a "prechamber," where the mixture is briefly heated by a glow plug. The driver turns on the ignition, then waits for an instrument-panel light to shine, telling him that he can step on the accelerator to start the engine. At 0DEG F., that can take a full minute.

Another problem is where to find diesel fuel; fewer than 5% of the nation's gas stations carry it. The diesel still emits more and blacker smoke than a gasoline engine--although, quite surprisingly, the smoke contains fewer polluting hydrocarbons and less carbon monoxide than gasoline exhaust. Finally, there is the matter of price: though quotations have not been firmly fixed, GM expects its diesel cars to sell for $750 to $840 more than an Olds powered by a conventional engine. Is there, nonetheless, a market? Probably. Mercedes-Benz introduced passenger diesels to the U.S. in 1952, and in the past few years, demand has grown dramatically. Today nearly 50% of all Mercedes sold in the U.S. come equipped with diesel engines.

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