General Motors and Ford said sales in America fell in April and their biggest Japanese rivals gained as rising gasoline prices pushed buyers toward models with increased fuel economy.

GM, the world’s largest automaker, reported an 11% decline in sales, and Ford said sales dropped 6.6%. Toyota and Honda, the biggest sellers of Japanese autos in America, had gains of 4.5% and 2.6%, respectively.

“It’s the price of gas that is driving all of this,” an auto analyst at Global Insight in Lexington, Mass., Rebecca Lindland, said. Gas prices are “making everything else more expensive as it drives up the cost of doing business.”

Reduced demand for light trucks such as sport-utility vehicles hurts the automakers based in America more than Asian companies, whose sales include a higher percentage of cars.

GM and Ford have been surrendering market share to Honda, Toyota, and other Asian competitors, which the government says have vehicles with greater average fuel economy. GM and Ford are also trying to end losses by cutting less profitable sales to rental-car companies and reducing reliance on rebates and other incentives.

The Asian automakers are expected to gain share for the ninth straight month when figures were tallied later yesterday.

April sales probably fell to an annual rate of 16.6 million cars and light trucks, from a 17.2 million pace in April 2005, according to a Bloomberg survey of analysts and economists.

Automakers have sold an average of 17 million vehicles in America each year this decade.

Ford, of Dearborn, Mich., sold 262,722 cars and trucks, according to a statement yesterday. Its figures include imports and heavy-duty trucks.

Ford said car sales rose 8.3% to 105,655, helped by new models such as the Ford Fusion, Lincoln Zephyr, and Mercury Milan sedans. Truck sales dropped 14.5%, led by a 42% decline for the Ford Explorer SUV and a 9.3% decline in F-150 pickups.

“We weren’t disappointed on overall sales, but cars did better and trucks didn’t do as well as we thought,” a Ford sales analyst, George Pipas, said in an interview. “I think it’s more fuel than anything. When you see these very rapid run ups, people get a little cautious.”

GM’s sales of light trucks fell 2.1%. Models such as the mid-size Chevrolet TrailBlazer SUV continued to decline while the Chevy Tahoe and other new, large SUVs gained. GM’s car sales fell 21% and Detroit-based GM sold fewer models to rental-car car companies. Chevy Malibu sales dropped 9%.

DaimlerChrysler AG, of Stuttgart, Germany, said sales fell 6.2% to 211,365 in April. The Chrysler group declined 8%. Mercedes-Benz increased 13% to 21,270, an April record, led by sales of luxury SUVs.

Rising fuel prices caused 62% of consumers to say they may rethink what vehicle they buy, the highest level since August 2005, a few weeks before gasoline reached a record, according to a study by Harris Interactive and Kelley Blue Book Marketing Research released last week.