WASHINGTON — No one begs Santa Claus for cheaper gasoline. Yet falling gas prices are shaping up as an unexpected gift for drivers — and for people on their holiday shopping lists.

The average price of gasoline has tumbled 49 cents from its peak this year to $3.29 a gallon, putting it on track for the lowest average since 2010, according to AAA. Because many Americans have had no pay raises, whatever money they’re saving on gas has freed up a bit more for other purchases.

And history shows that when gas prices drop, consumers become more likely to splurge on dinners out. Impulse buys at the mall seem like less of a stretch. More people buy a gas-station gift card after fueling up. Many retail analysts have forecast a ho-hum sales gain of around 2 percent this year; others predict an increase of up to 3.9 percent. But steadily cheaper gas could send holiday sales shooting above 5.4 percent, analysts say.

“Every little thing moves the needle at this point,” said Carl Riccadonna, senior U.S. economist at Deutsche Bank. “The benefit at this time of the year certainly helps retailers, since it is not spread evenly throughout the year.”

Tom Kloza, chief oil analyst at the Oil Information Service, foresees the average price drifting down, as it typically does this time of year, to as low as $3.05 by year’s end.

For retailers, the best-case scenario would be for the national average to breach $3 a gallon, a psychological barrier that could help accelerate spending.

Cheaper gas could help build on the momentum of 2 million more Americans finding jobs this year. It might also help shore up consumers’ fragile confidence in the economic recovery.

Riccadonna estimates that breaking $3 gas would lead the average shopper to spend $47 more over the holidays. That figure would translate into $15 billion worth of extra shopping — possibly the difference between lukewarm and red-hot sales growth.

Prices briefly dipped below $3 in five states — Arkansas, Kansas, Missouri, Oklahoma and Texas — before rising above that threshold again.

Some service stations have been charging less than $3 around Tucson, Ariz., where Seth Nilson, a high school teacher, and his wife, Cristi, are enjoying more time at restaurants.

“We have definitely gone out to eat more lately,” Nilson said. “She tends to cook less when gas prices are low.”

Many consumers think of gas prices in 50-cent increments, said Britt Beemer, head of the consumer behavior consultant America’s Research Group. Based on his firm’s research, shoppers would spend more freely if gas settles below $3 or $2.50. They would likely step up purchases at grocery stores or spend $35 on a gift instead of the $25 they might have planned, Beemer said.

“A 10-cent drop doesn’t really change the equation much,” Beemer said.

Still, smaller declines in gas prices matter, too, even if they don’t register as clearly with consumers.