SANTA MONICA, Calif. — TrueCar.com reported last week that December sales could top 1.37 million units, which would represent a 10.3 percent increase vs. a year ago and a 19.9 percent increase vs. November.

If the vehicle information site’s prediction holds true, the feat would translate into a seasonally adjusted annualized rate of 15.6 million units, up from the 13.6 million rate recorded in December 2011 and up from 15.5 million un November.

So far this month, retail sales are up 9.2 percent compared to December 2011 and up 23.6 percent from November 2012. Fleet and rental sales are expected to make up 16.5 percent of total industry sales in December, TrueCar said.

The expected increase would be achieved despite incentive spending being down 9 percent from the year-ago period, with the average spend per unit expected to come in at $2,409. However, that per unit level would be a 4.3 percent higher vs. November.

Used-car sales, according to TrueCar, are expected to total more than 3.49 million units, a 6.6 percent increase from December 2011 and a 13 percent increase from November.

“December continues the trend of exceptional sales due to strong manufacturer incentives, specifically lease and finance deals, and the demand due to Hurricane Sandy in the Northeast,” said Jesse Toprak, senior analyst for TrueCar.com. “Even with the fiscal cliff still needing to be resolved, automakers can expect a strong year for new car sales in 2013.”