DETROIT — When gasoline prices rise, the biggest beneficiary in the auto industry seems to be Toyota.

Riding record sales of its Prius hybrid and increased sales of the Camry, Corolla, Yaris and other cars, Toyota posted a U.S. sales gain of 14.1 percent in May for its highest monthly total ever.

With gasoline prices topping $3 per gallon nationwide, Toyota Motor Corp. sold just over 24,000 gas-electric Priuses, a whopping 185 percent increase over last May, the company said yesterday.

The Prius, which gets an estimated 55 miles per gallon in combined city and highway driving, helped boost Toyota's U.S. sales above Ford Motor Co., which saw a decline of 6.9 percent as it continued to cut low-profit sales to rental companies.

General Motors Corp., which also said it benefited from high gas prices in some segments, reported that its sales rose 9.7 percent, helping boost industry sales by 5 percent during a month that many analysts expected to be lackluster.

DaimlerChrysler AG's sales rose 3.9 percent and American Honda Motor Co. rose 2.5 percent. Nissan Motor Co. posted a strong gain at 7.4 percent.

Paul Ballew, GM's executive director of global market and industry analysis, said that since 2005, several trends have emerged when gasoline prices rise in the spring, and this year was no different.

Buyers tend to shift from trucks to cars, luxury car sales tend to weaken, small- and mid-sized car sales rise and people tend to choose four-cylinder powertrains over larger engines, Ballew said.

The industrywide mix of cars and trucks was about equal in May, while trucks normally account for about 55 percent of the market, according to Ballew.

But like 2005 and 2006, Ballew predicts a gradual drop in gasoline prices during the summer and a return to the 55 percent truck mix later in the year.

Still, he said GM was helped in some areas by higher gas prices because its pickup trucks get better gas mileage than competitors, as do its mid-sized crossover vehicles. And it has a wider array of mid-sized and small cars than in the past, he said.

"We're much better positioned than where we were," Ballew said.

GM, the industry's top seller, said it sold 371,056 light vehicles last month. Car sales, including the Chevrolet Impala and Saturn Aura, rose 16.2 percent to 150,979, while light truck sales, including the Chevrolet Silverado and GMC Sierra pickups, gained 5.6 percent to 220,077. GM's sales include the European Saab brand.

The Silverado again passed Ford's F-Series pickups as the top-selling vehicles in the U.S.

GM said its retail sales rose 12.8 percent compared with May 2006.

Toyota, which has been gaining market share in the U.S., sold 269,023 Toyota and Lexus vehicles in May, topping its previous monthly record of 242,675 set in March. Car sales rose 16.2 percent to 168,270, while light truck sales, including the Tundra pickup, rose 10.9 percent to 100,753.

Industrywide U.S. sales in May rose to 1.56 million from 1.49 million in May 2006, according to Autodata Corp.