DETROIT – U.S. auto sales cooled off in May as buyers dealt with shortages on dealer lots, higher gas prices and sharply lower incentives. And the deals aren’t likely to come back until the end of this summer.

Some experts are advising people to delay their purchases if they can.

“If you don’t have to buy, wait until fall. If you lease a car, extend it,” said Edmunds.com chief Jeremy Anwyl. Whatever deals buyers see will be “fleeting,” he said.

Consumers heard that message in May. U.S. auto sales were expected to be around 1 million cars and trucks, down 8 percent from April and 4 percent from last May.

General Motors Corp. said its sales fell 1.2 percent, as falling pickup truck sales offset strong sales of more fuel-efficient cars and crossovers. It was the same story at Ford Motor Co., which saw sales fall 2.4 percent for the month. Pickup sales fall more than 10 percent at both companies.

Don Johnson, GM’s vice president of sales, said consumers are taking a wait-and-see approach as gas prices fluctuate around $4 per gallon. Construction remains weak, hurting truck sales.

Even so, Johnson feels consumer confidence over the long term remains strong and sees pent-up demand among drivers who kept their vehicles longer than usual during the recession. He said GM is keeping its full-year sales forecast in place, and expects sales and incentive spending to rise toward the end of the summer.

“All things considered, we continue to believe the recovery remains on track,” he said.