GM turns the diesel engine into a luxury-car standard

The "image" of the diesel engine, long used in large trucks as well as off-road equipment and locomotives, has been tamed. In fact, it has almost been made genteel. A diesel might be expected in some cars without raising an eyelid. Somehow, a diesel in a German-built Mercedes-Benz doesn't warrant much attention any more. But a diesel engine in the most prestigious Cadillac of them all, the front-wheel-drive Seville -- and the standard engine at that -- does cause one to ask what is happening in the marketplace.

What it shows is General Motors' commitment to the diesel despite all the stumbling blocks in the way.

More than one-third of all Cadillac Sevilles now being sold are powered by a diesel engine. The rest of the buyers opt for the 6-liter V-8 gasoline-burning engine with digital electronic fuel injection -- and save some money as well. The gas-engine Seville is 300 pounds lighter than the diesel version.

Perhaps even more than the Seville's luxury, the 5.7-liter diesel V-8, however, is what really sets the car apart. Its counterpart from Ford, the Continental, offers no diesel; and neither does Chrysler.

The 1980-model Cadillac Seville is listpriced at somewhere around $20,000, but the price runs up a few more thousand if the buyer opts for the Elegante paint and trim package, which GM bills as the "ultimate Seville" with its standard leather seats, distinctive console, and special two-tone colors.

As expected, it's a joy to drive, not just because of the luxury, but because it holds the road well, even in a high cross wind. It steers and brakes as well as any car in its price range should. Disc brakes are used front and rear.

Somewhat controversial is the so-called bustle trunk, an attempt to copy the back of the old Rolls-Royce of many years ago. If Rolls did it, it must be all right, GM designers seem to feel. Some potential Seville buyers are't so sure. (Rolls-Royce hasn't come around to a diesel engine yet, and it probably never will.)

Nonetheless, the Seville is a very civilized car, elegant, well insulated against outside noise as well as from the engine, and performance is -- well, it is a diesel. Even so, GM has struck a good balance between fuel economy and acceleration.

The Seville switch to the diesel is of more than passing importance because it could be the one engine that keeps the elegant luxury sedans on the road in the mid-and late-1980s as fuel becomes tighter, and especially if rationing goes into effect sometime in the future. A gasoline-engine luxury car gets much less distance on a gallon of fuel than a diesel.

Cadillac expects to sell 42,000 diesels, available as an option in the rest of the Cadillac lineup, this year.

In a week-long test drive of the Seville, I chalked up around 20 to 21 miles to a gallon, a few miles below the even more expensive Mercedes-Benz 300D. Undoubtedly, GM engineers will continue to lighten the Seville, or its successor , even more in the future -- and the mileage will therefore go up.

The car I drove was loaded with options, including an automatic lighting system which turns the headlights on when they're needed, dims the high beams without any move on the driver's part, and turns the lights off -- after the motorists are safely inside the house. However, the automatic dimmer is a constant frustration as it flashes up and down with monotonous regularity. It responded as fast to a street light as to a car bearing down in the other direction. The best solution was to go to manual operation of the lights, I found.

The emergency brake also is hard to operate. While it releases automatically when you put the car in forward gear, I found I had to reach well under the hood and free it m anually when I wanted to back up. But these are among the few faults on the car.

Seville took about 20 percent of the Cadillac market in 1979 and is running a bit higher for 1980. Total Cadillac sales, however, are expected to run about 30,000 less than a year ago when the prestigious GM division sold 328,000. About 53,000 are expected to be Sevilles. In 1978 Cadillac sold 348,000 cars, an all-time record.