What’s driving an increase in auto sales?

New car sales numbers come out on Tuesday. Many expect the holidays to come early for automakers, with the economy up and gas prices down.

Analysts expect Americans bought as many as 1.3 million new vehicles last month, a nice boost over the previous November. That’s in part because more dealers have hopped onto the Black Friday craze.

They’re also selling pricier vehicles, meaning bigger transactions than ever before. Independent consultant Alan Baum says today’s new car buyer is well off.

“Hence not only the increase in sales volume, but the increase in transaction prices, and therefore profits,” says Baum. “All of that is of course very good for the car companies.”

Or perhaps we should call them light truck companies. That’s where the action is.

“The small crossover SUV market has really skyrocketed, really at the expense of cars,” says Rebecca Caldwell at Edmunds.com. “Light trucks have outsold cars for over a year now.”

A big winner in this space is Jeep. Its sales grew a whopping 45 percent the past year, revving up a broader comeback for parent company Chrysler.

One factor nudging up truck and SUV sales, Caldwell says: low gas prices.