The Customs Service says it will classify imported sport utility vehicles like the Suzuki Samurai and most small vans as trucks, subjecting them to duty rates 10 times higher than those for cars.

Deputy Customs Commissioner Michael Lane said that in the past, these vehicles sometimes had been classified as cars, upon which a 2.5 percent duty is imposed, and at other times as trucks, subject to a 25 percent duty.The deciding factor often was whether the vehicles were fitted with back seats and other amenities.

Lane said auto industry officials have estimated the ruling could affect 100,000 to 250,000 or more vehicles, many of which will be switched from the car to truck category and could net the government hundreds of millions of dollars in higher tariffs.

Wednesday's ruling specifically applied to Suzuki's Samurai and YOE, but Customs officers have been instructed to use the same standard in classifying other imported vehicles, the agency said.

Chrysler Corp. spokesman Al Slechter said the automaker was "ecstatic" about the ruling. He said it would end manipulation of the tariff system and increase Treasury revenues.

Suzuki spokeswoman Laura Segall said most Samurais already were being imported as trucks but that the company was "disappointed" the Customs Service had ruled against allowing some sport vehicles to be admitted as cars.

Vehicles imported as trucks are not covered by the voluntary restraint agreement under which Japanese automakers limit the number of cars brought into the United States.