New vehicle sales, including fleet deliveries, are projected to reach approximately 1.7 million units, a 12.8% increase from 2014, according to a report by True Car. 

A key finding of the report shows an expected registration mix of 85.8% retail sales and 14.2% for fleet versus 84.7% retail and 15.3% fleet last December, fleet sales slightly decreased by 1.1 percent. 

This sales growth will also push total annual light vehicle sales to a record 17.5 million units, up 6.1 percent from a year ago and it should carry over into 2016. 

Incentive spending by automakers averaged $3,063 per vehicle in December, up 3.9 percent from a year ago and down 0.4% from Nov. 2015.

Strong economic factors that boosted the industry remain in place such as low gas prices, a low unemployment rate, and a healthy gross domestic product (GDP). All these factors are expected to continue into the new year. Another factor that has contributed to sales growth would be the federal fund rate, despite the recent 0.25-point increase.

Sales of mass-market small utility vehicles, including both subcompact and compact models, are up 419% in 2015 versus 2000.

The top-selling car for 2015 was the Toyota Camry, the top-selling utility vehicle was the Honda CR-V, and the top-selling premium vehicle was the BMW 3 Series.