AUTO INDUSTRY : U.S.-Built Car, Truck Sales Rise Sharply : Autos: They log a 24% gain in late January. But when imports are included, total vehicle sales for the month were flat.

Sales of domestically made cars and trucks soared 24.5% in late January, but total sales, including imports, finished flat for the month, according to figures released Wednesday by the auto makers.

U.S.-built vehicles sold in late January at a daily rate of 40,302, against 32,232 for the same month last year. There were nine selling days in the latest period and 10 last year.

But for the entire month, vehicle sales were off 0.5% from January, 1992, including the results for the nine major Japanese and 10 European auto makers that sell vehicles in the United States.

“It isn’t where we were in mid-December, but still it was good to see it,” said Nick Lobaccaro, an auto industry analyst with S. G. Warburg & Co. in New York.

Domestic cars and trucks sold at a projected annual rate of 12.6 million units in the Jan. 21-31 period, up from 10.2 million a year earlier. Car sales recorded their strongest period since last July, ending at a 7.8 million projected annual rate.

General Motors Corp. reported 10.1% higher car sales in late January, a rare event since the auto maker started cutting back on low-profit sales to daily rental companies.

Ford Motor Co. continued building on strong sales in the first two periods of January. The No. 2 auto maker’s car sales were up 26.7%, and its truck sales rose 30.5%.

Chrysler Corp.’s late January vehicle sales were estimated by Ward’s Automotive Reports to be up 39.8%. Chrysler’s actual monthly sales were up 31.6%, including several thousand cars and trucks it imports from Mitsubishi. Chrysler reports sales on a monthly basis only.

For the month, total car sales, including imports, rose 4%, and truck sales, including minivans, sport-utility trucks and pickups, fell 7.4%.