General Motors, Ford Motor, and DaimlerChrysler AG, reported lower auto sales in America for a third straight month as Asian automakers led by Toyota Motor likely gained market share.

GM, the world’s largest automaker, said yesterday its U.S. December sales fell 10% to 392,041 cars and trucks. Ford, the second-biggest American carmaker, said its sales dropped 9% to 267,881, while DaimlerChrysler, no. 3 in America, said Chrysler and Mercedes-Benz vehicle sales fell 2% to 220,641. Toyota’s sales rose 8.2% to 203,279.

Cars and light trucks in America sold at an annual rate of 16.9 million units last month, down from 17.9 million a year earlier, according to a Bloomberg survey of analysts and economists. Sales in 2005 probably matched the 16.9 million of a year earlier.

“The domestics have been suffering and the imports have been gaining,” the president of automotive data serviceEdmunds.com, Jeremy Anwyl, said. “The real question is: What’s going to happen in 2006?”

Sales at Chrysler, GM, and Ford are falling as buyers defect to Toyota, the world’s second-biggest automaker, and other Asian rivals. The declines are a reversal of gains in June and July, when American carmakers offered employee discounts for all buyers.

GM hasn’t had a sales increase since July, and Ford reported lower sales in America each month since August.

Toyota’s sales for all of 2005 rose 10% to 2.26 million vehicles, the biggest unit increase among all automakers.

GM’s December car sales fell 19% to 131,687 as models such as the Chevrolet Impala fell 22% and the Chevy Monte Carlo declined 36%.

Light-truck sales declined 4.7% as Chevrolet Suburban sport-utility vehicles fell 36% and the Chevy Tahoe dipped 12%. Sales of large pickups such as the Chevy Silverado rose 1.7%.

For the year, GM reported a 4% decline to 4.52 million vehicles.

Chrysler sales dropped 5% to 189,449 in December, the Stuttgart, Germany-based company said in a statement. The U.S. unit still posted its second straight annual sales gain. Mercedes-Benz sales in December increased 17% to 31,192, bringing them to a record for the year.

Chrysler started offering a debit card with $2,400 toward gasoline purchases along with free maintenance for two years and extended warranties on most 2005 and 2006 models after October sales fell 3.1%. Chrysler yesterday extended the program until January 9, when it will announce new incentives, a spokesman, Kevin McCormick, said.

Sales of Dearborn, Mich.-based Ford’s F-Series pickup trucks, the bestselling line of vehicles in America, fell 6.2% to 89,491. The company sold 901,463 F-Series in 2005, a 4% decline, while still hitting its target of selling at least 900,000 of the vehicles.

Nissan Motor, Japan’s no. 2 carmaker, sold 91,253 cars and trucks last month, down 1.1% from a year earlier, Jed Connelly, the automaker’s head of American sales, said. For all of 2005, Tokyo based Nissan sold 1.076 million vehicles to American drivers, up 9.1% from 2004 and the first time the company has exceeded 1 million units in a calendar year, Mr. Connelly said by phone from Nissan’s Canton, Miss., assembly plant.

Honda Motor’s December sales in America fell 3.3% to 132,800 cars and trucks. Cars posted a 16% decline, led by a 31% drop in Accord sedans, while light-truck sales rose 14.1% on an 18% gain in Pilot SUV sales and the addition of its Ridgeline pickup.

“The Asians continue to stay the course,” an analyst with Autodata Corporation, David Lucas, said.

GM shares, which fell 52% last year, rose 51 cents to $19.41 at 4 p.m. in New York Stock Exchange composite trading. Ford gained 18 cents to $8.01, and DaimlerChrysler’s shares were down 24 cents to $53.51.