P.M. BRIEFING : Big 3 Car, Truck Sales Soar 11.8%

DETROIT —  Mid-September car and truck sales by the nation’s Big Three auto makers soared 11.8% from last year, in large part because of a strong performance by General Motors Corp. trucks, the companies said today.

With just one 10-day sales reporting period left in the model year, GM, Ford Motor Co. and Chrysler Corp. said they sold cars and light trucks at an average daily rate of 35,445 from Sept. 11 to 20, compared with 31,714 in the same period last year.

Car sales rose 7.1% while truck sales rose 19.5%, mostly because of a 46% rise in GM sales. GM spokesman Terry Sullivan said increases occurred in all GM light truck lines. The 1988 model year was the third-best in history, with about 15.6 million cars and trucks being sold, at a ratio of roughly two cars per truck. The past calendar year was the second-best on record with 15.8 million vehicles purchased.