Although auto makers have traditionally offered incentives to stimulate sales of slow-selling models, G.M. officials said that customers had come to expect incentives.

Occasionally, the code for a slow-selling or old model of a television set or other device won't be programmed into the memory chip.

Now they nab manufacturers' closeouts and slow-selling models of better brands and stamp their own brand names on imports.

Foremost are the enormous development and retooling costs of rushing new cars and trucks to market to replace the mostly slow-selling models it has now.

Although the company has many slow-selling models that are several years old, Mr. Lutz said, the response to new vehicles has been overwhelmingly positive.

The car maker's current incentives will extend through April 30 to try to move some of its slow-selling models before the 1991 versions appear.

Last year, Corvette had 39 percent of a weakened sports car market, according to Chevrolet, as the Japanese withdrew their slow-selling models to focus on trucks.

The highly visible and popular customer rebates were introduced in the mid-1980's to stimulate sales of slow-selling models and reduce large inventories.

The car is 11 inches longer than the slow-selling model it replaces.

Pumping slow-selling models into fleets, even at a lower profit than at retail, is often viewed as better than closing factories and laying off workers.