The cost of cars has been climbing, so any discounts are welcome. The average transaction price of a new vehicle in October was about $37,000, up about 4 percent from a year earlier, according to the dealers association.

There can be drawbacks to shopping in December. You may feel stressed or rushed with other holiday shopping, or lack the time to research your purchase and negotiate with car sales employees. In that case, Mr. Bartlett said, consider breaking your car hunting into two trips — one visit to gather information and test-drive, and a second to negotiate. Cold weather also means you and your family will be wearing bulky coats, which should ideally be removed when you sit in the car, he said, so you can truly gauge what the seats feel like.

And consider whether a new car may be a stretch, given other spending during the holidays. “It’s a great time to save money,” Mr. Bartlett said, “but only if it’s the right time for you to get a car.”

While you may find the price you want at year-end, the car itself may not be the specific model you were seeking. Perhaps it has an “interesting” color, Mr. Lyman said, or an odd mix of options — a top-grade stereo, say, but no leather seats. So be sure that the price you’re getting is worth the trade-off.

“Do you really want to drive an orange car?” Mr. Lyman said.

Here are some questions and answers about buying a car:

What interest rates are currently available on car loans?

Average loan rates have been falling in recent months. In November, the average rate for a new-car loan was 5.5 percent, down from 5.7 percent in October and 6 percent in November 2018, the automotive site Edmunds said. Nearly a quarter of shoppers who financed their car purchases in November got an interest rate below 3 percent.

Still, the rising cost of cars means that more people are taking out loans with longer terms to lower their monthly payments. The average new-car loan in the third quarter of this year was about $32,500 and stretched for about 69 months — almost six years, according to Experian Automotive, an arm of the Experian credit bureau. The average payment for new vehicles was $550. Lengthier terms can put borrowers “under water” for longer periods — meaning they owe more than the car is worth. That could force them to come up with extra cash if they trade in the car or sell it before they pay off the loan.