Rising gas prices and consumers looking to buy more fuel-efficient cars helped give GM a sales boost, even as economic jitters and parts shortages in earthquake-ravished Japan slowed showroom traffic elsewhere in the industry.

Retail sales for GM's four brands - cars and trucks sold by dealers - were up 25 percent in April over the same month last year, and up 4 percent compared to March, despite GM pulling back heavily on incentives. Fleet sales were up 31 percent in April over the same month last year and accounted for about one-third of sales during the month

GM reduced discount spending by $400 per vehicle from March to April, said Don Johnson, GM's vice president of U.S. sales.