U.S. auto sales rose to the highest rate in 16 months in December, and major automakers forecast the recovery would gather momentum in 2011 as the industry distances itself from one of its deepest slumps ever.

Auto sales are one of the first snapshots of U.S. consumer demand. The 11 percent rise in December auto sales stands as the latest in a string of indicators including unexpectedly strong factory orders for November pointing toward growing confidence in the recovery.

U.S. auto sales rose more than 11 percent in 2010 to almost 11.6 million vehicles, snapping a four-year slide that forced the Detroit automakers into a wrenching restructuring that included government-directed bankruptcies for GM and Chrysler.

In a year-end surge that took the industry by surprise, the annualized sales rate for December jumped to almost 12.6 million vehicles, the highest rate since August 2009 when the U.S. government's Cash for Clunkers trade-in incentives touched off a short-lived boom.

Major automakers, including Ford and GM, said they expected that sales for 2011 could top the 13 million-vehicle level. Analysts said that estimate could prove conservative if the momentum of recent months continues.

We have seen real improvement in actual consumer demand, particularly in the last quarter of 2010, TrueCar.com analyst Jesse Toprak said.

General Motors Co's sales rose 7.5 percent from a year earlier in December. Ford Motor Co's sales rose 6.7 percent and the carmaker overtook Toyota Motor Corp as No. 2 in the U.S. market for 2010.

The gains for the top U.S. automakers underline the stunning turnaround in the fortunes of GM and Ford. Shares of Ford, which avoided a bailout, have gained more than 70 percent over the past year.

Shares of GM are up 13 percent from a November initial public offering that marked the automaker's reemergence as a listed company after a U.S. government bailout.

GM shares closed up 2.3 percent at $37.90 and Ford stock gained 0.75 percent to $17.38 on Tuesday.

Toyota, which has been struggling with the aftermath of a safety crisis that surfaced in late 2009, posted a sales decline of almost 6 percent in December.

For 2010, Toyota sales were almost flat from 2009, the worst of the downturn when industry-wide sales were at the lowest level since the 1980s.

Other major automakers posted double-digit percentage gains for December. Chrysler sales rose 16 percent and Nissan Motor Co sales rose 28 percent. Sales for Honda Motor Co were up 21 percent.

Hyundai Motor Co's sales gained 33 percent. Its affiliate Kia Motors posted a 45 percent gain, continuing a trend that has seen the Korean brands take share from rivals in a recovering U.S. market.

Hyundai has benefited from Toyota's stumbles, an improved reputation for quality and its ability to undercut established competitors on price.

South Korean carmakers will continue to be ahead of Japanese rivals because of new model effects, the favorable currency and improved brand image, Korea Investment & Securities analyst Suh Sung-moon said.

He expected Hyundai and Kia to further increase their U.S. market share to 8.4 percent this year, from last year's 7.7 percent.

Shares in Hyundai and Kia rallied 4.7 percent and 3 percent, respectively, in Asian trade on Wednesday, while Honda fell 0.6 percent and Toyota and Nissan rose less than 1 percent.

CONFIDENCE ON THE RISE

Major automakers cited a range of negative factors that represent an overhang for the U.S. economy and auto sales, including the drag from a still-weak housing market, high unemployment and the threat of rising gasoline prices.

But executives and analysts said the increased availability of loans for consumers, rising used car prices and improving consumer confidence had tipped the balance toward continued recovery for the auto industry.

I think people are a lot more confident in making big purchases now. That's the story of the fourth quarter, Al Castignetti, the head of Nissan sales, told Reuters. I think we're going to see slow, steady growth.

GM and Ford both reported a jump in sales to retail customers through dealerships, a category considered the best indicator of underlying demand.

GM said it expected industry-wide U.S. sales of about 12.7 million to 13.2 million vehicles in 2011, excluding heavier work trucks. Ford forecast sales at about 12.2 million to 13.2 million vehicles on the same basis.

Nicholas Colas, chief market strategist at brokerage ConvergEx Group, said the stronger GM sales for December could force analysts to raise earnings forecasts for the fourth quarter.

The key variable here is pricing, which improved in the month, Colas said in a note for clients.

In a sign of increasing confidence in the pace of recovery, Ford said it would begin to push its inventory levels over the 400,000-vehicle level that it has maintained in recent months.

One of the bright spots for the Detroit automakers has been the rise in sales of trucks in recent months, including the pickup trucks used heavily in construction and by other small business owners.

For December, sales of Ford's market-leading F-Series pickup trucks were up almost 14 percent. Sales of the rival Chevy Silverado rose 32 percent.

Sales of trucks and SUVs remain key for the U.S. automakers because they are more expensive vehicles that carry wider profit margins than smaller and more fuel-efficient cars.

OIL PRICES A RISK

Rising oil prices in 2011 could present a renewed challenge to Ford, GM and Chrysler even after efforts by all three automakers to diversify their product offerings and push into more fuel-efficient small cars, analysts said.

I would label that as my number one risk to watch for 2011, said Paul Ballew, chief economist at Nationwide.

Toyota, which will detail plans for a range of vehicles based on its market-leading Prius hybrid platform at the Detroit auto show next week, said it could gain ground at a time of rising gasoline prices in 2011.

The automaker forecast a double-digit percentage gain in 2011 sales, outpacing the industry. That would come as U.S. gasoline prices head toward $4 per gallon, a rise of about 30 percent from current levels, it said.

We're coming off what was arguably the most challenging time in our 53-year history, Don Esmond, senior vice president at Toyota's U.S. sales arm, told reporters.

Beyond the United States, Ford said it expected global sales to hit a record level of between 75 million and 85 million vehicles in 2011 from about 72 million in 2010.

The global economy is reaching a dynamic phase, Ford chief economist Ellen Hughes-Cromwick said.

The engine of growth for the global auto industry is expected to remain developing markets led by China and India.

Car sales in India were reported strong in December with Fitch expecting sales growth of up to 15 percent in 2011 driven mainly by a growing middle class and more financing opportunities.

(Reporting by David Bailey, Deepa Seetharaman, Kevin Krolicki and Bernie Woodall; Editing by Matthew Lewis and Lincoln Feast)