NEW YORK (CNNMoney.com) - Sales slumped at Detroit's Big Three in December, capping very different years for the automakers, as Asian automakers made further inroads with U.S. car buyers.

Troubled General Motors (Research) and Ford Motor Co. (Research), both plagued by declining market share this year, saw their sales slumps continue in December. Meanwhile No. 3 Chrysler Group capped a very strong year with a smaller drop in December sales. Import brands generally reported sales gains for December as well as the full year.

GM, the world's No. 1 automaker, said U.S. December sales of cars and light trucks tumbled 10 percent from a year earlier to 384,620. That left the automaker's full-year sales down 4.3 percent to 4.5 million vehicles.

Car sales fell 7 percent to 1.7 million for the year while sales of light trucks, including sports/utility vehicles, pickups and minivans that have been at the core of GM's profits in past years, dipped 2 percent to 2.7 million.

The one piece of good news in the results for GM was that Chevrolet edged past rival Ford Motor Co.'s Ford unit to become the nation's best-selling brand for the first time since 1986.

Chevy, which was nearly tied with Ford in 2004, had sales of 2.7 million vehicles compared with Ford's 2.6 million. But Chevy took that lead as its sales fell a bit less than Ford's -- a 3 percent drop compared to a 4 percent drop at No. 2 Ford.

Meanwhile Ford Motor ended what was also a very weak 2005 with December sales tumbling 9 percent. That gave it a 5 percent decline in full-year sales from 2004 to 3.2 million vehicles, even as car sales rose 2 percent.

Ford's sales of light truck models, which it had depended upon for profits, fell 8 percent for the year and 10 percent in December. The car models ended a good year with a nearly 6 percent drop in December.

Ford's luxury brands -- Lincoln, Jaguar, Volvo and Land Rover, all posted double-digit declines in sales for the year, as did most of its SUV models. Things weren't as bad for pickups, but its F Series pickup truck, the nation's best-selling vehicle once again, saw sales fall 4 percent to 901,463.

By comparison, DaimlerChrysler (Research) saw its key North American unit Chrysler Group post a 5 percent gain in U.S. sales for the year, even as it posted a 5 percent drop in December sales.

Its luxury division, Mercedes Benz USA, saw a 17 percent gain in December sales, but only a 1 percent gain in full-year sales. Combined U.S. sales for the nation's No. 3 automaker rose 4 percent, to 2.5 million vehicles, on the strength of Chrysler sales.

Even with a gain in year-over-year sales, DaimlerChrysler almost lost its No. 3 ranking in U.S. sales to faster-growing Toyota Motor, which posted a 10.1 percent gain for the year to sell 2.3 million cars and light trucks.

Toyota's gains were driven by a 17.5 percent increase in sales for its car models during the year. Light trucks posted a far more modest 2 percent increase.

Its Camry was once again the nation's best-selling car model during the year with 431,703 sold. Its Prius hybrid gas-electric powered car, which got a lot of attention in a year of record gasoline prices, saw full-year sales double to 107,897.

About 62 percent of Toyota's U.S. sales were built at North American plants, slightly down from the 63 percent share a year earlier.

Japanese competitor Honda Motor also made smaller gains, posting a 5 percent gain to 1.5 million vehicles sold for the year. Its December sales followed the Big Three lower, falling 3 percent.

Unlike Toyota, Honda's car sales slipped slightly, while its light trucks carried the automaker, posting a 14 percent gain for the year.

Other import automakers to make reports early Wednesday -- BMW, Audi and Porsche and Subaru -- all posted full-year gains in sales as well as gains in December sales.

General Motors stock was up about 2% in afternoon New York Stock Exchange trading, while Ford stock was up almost 3% and DaimlerChrysler stock slipped a fraction.

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