The seemingly unstoppable auto industry enjoyed growing sales yet again in January, General Motors and Ford leading with the biggest sales gains in the country for the month.

Vehicle sales have been boosted by rising consumer confidence in the economy as well as the most affordable gas prices seen in the United States in years.

"This is going to be seen as a good month and a continuation of the trends we've seen," Maryann Keller, a Connecticut-based independent automotive consultant, told Bloomberg Radio. "It's the fact that lenders are willing to make very good financing offers, both leasing and loans, to customers today with somewhat compromised credit, where three or four years ago they wouldn't do it."

The adjusted annual sales rate for January is estimated to have risen from 15.3 million vehicles to 16.5 million year over year.

The GMC brand jumped 29 percent to help boost GM's 18 percent rise in sales, while Chevrolet posted a 20 percent rise in sales as consumers selected more pickup and sport utility vehicle options.

After making major changes to its best-selling model, Ford posted a 16 percent sales increase for light vehicles and said the F-Series pickup line saw its best January sales since 2004.

Toyota reported a 15.6 percent year-over-year rise on a volume basis in January with sales of 169,194 units.

"The year is off to a strong start as the sales momentum we saw in 2014 continued into January," Bill Fay, Toyota division group vice president and general manager, said in a statement. "Highlander, RAV4 and Corolla all set January records."

Fiat Chrysler posted a double-digit sales increase as well, rising 14 percent year over year for U.S. sales of 145,007 units and the group's best January since 2007. Recently renamed as FCA US, the group has had a 58-month streak of year-over-year sales gains.

Nissan was boosted by sales of its Altima sedan, which rose 17 percent for a January record of 26,408 units. The automaker posted an 11 percent rise in sales overall. Honda sales came up slightly short of a 13 percent forecast for gains of 12 percent. 

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