NEW YORK (TheStreet) -- Auto sales continued to mirror the economy's strength in December, with experts forecasting a gain of 10% or more over the same month a year earlier.

"Many factors have helped car sales recently," says Edmunds.com analyst Jessica Caldwell, in a prepared statement. "Low gas prices, a record stock market and the improving economy are making people feel more financially comfortable, and even the weather has cooperated, for the most part."

Sales also benefited because December 2014 had 26 sales days, one more than 2013.

Kelley Blue Book forecast a 9.8% gain to 1.49 million units sold. Edmunds forecast an 11.4% gain to 1.5 million vehicles sold. And J.D. Power also forecast sales of 1.5 million.

For the month, Fiat Chrysler (FCAU - Get Report)   is expected to lead the pack. Edmunds has Chrysler sales up 25% for the month, and Kelley Blue Book sees a 20.5% gain. That would lead to a market share of 14.2%, up a full percentage point for the year.

Edmunds also sees gains of 15% for Toyota (TM - Get Report) , 14% for GM (GM - Get Report) and 4% for Ford (F - Get Report) , while Kelley Blue Book foresees 11% for Toyota, 7% for GM and 4% for Ford.

"Toyota has had a quietly solid year with strength in line with the industry, but it currently has two of the top three selling cars with its Camry and Corolla, which are up 5% and 11% respectively this year," Kelley Blue Book said.

As for Ford, its transition to the 2015 F-150, which is beginning to reach dealerships, will be closely watched. The model changeover in the best-selling U.S. vehicle means December will belong to competitors.

"Full-size trucks should experience a normal seasonal spike in December, which is aided by gas prices at a five-year low," said Kelley Blue Book analyst Alec Gutierrez, in a prepared statement. "As the all-new Ford F-Series begins to make its way to dealerships, General Motors and Fiat Chrysler stand to gain the most sales in December."

Based on its December forecast, Edmunds said overall U.S. light vehicle sales will rise 6% in 2014 to 16.5 million units. U.S. spending on new cars is expected to have risen from $90.8 billion in 2013 to approximately $100 billion in 2014.

New vehicle sales have risen steadily since falling to 10.3 million in 2009. Sales totaled 15.6 million in 2013. Sales last reached 16.5 million in 2006.

Looking ahead to 2015, Kelley Blue Book forecasts sales of 16.9 million, while TrueCar expects 17 million units.

"We see a convergence of favorable economic circumstances pushing auto demand up to pre-recession levels, including continued gains in the job market, the best consumer sentiment in eight years and low fuel prices," said John Krafcik, president of TrueCar (TRUE - Get Report) in a prepared statement.

"Ford's redesigned F-Series pickups, Mazda's CX-3 crossover as well as the Mercedes GLA luxury crossover should be standout models in their respective segments next year," Krafcik said.

Written by Ted Reed in Charlotte, N.C.

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This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.