Vetatur Fumare/Flickr
Economists forecast that sales rose at a seasonally adjusted annual rate of 17.7 million, compared to 17.8 million in November.
The pace of sales in December could make 2016 another record year of sales. Sales last year were driven by lower gas prices, the relatively high average vehicle age for cars on the road (over 11 years), and easy credit.
Also, consumers were buying pickups and SUVs, the vehicles that bring in the most profits.
In 2015, 17.5 million new cars and trucks were sold.
Because the market is cyclical, it's possible that the plateauing some strategists warned about last year could have happened in 2016. Interest rates are slowly rising, commercial banks are tightening auto lending standards, and the subprime delinquency rate - missed payments among people with a tarnished credit history - is creeping higher.
Also, carmakers, who have dished out lavish incentives to attract buyers, may face higher costs if the new administration implements trade restrictions. On Tuesday, President-elect Donald Trump threatened a tariff on General Motors for manufacturing a version of the Chevy Cruze in Mexico.