Mr. Strom also owns a pickup truck, which he uses mainly to haul his boat. When he runs errands, he drives his Smart, which he says is getting 45 miles a gallon.

“I had to smile the other day when I filled my tank for $18 and the guy next to me had a Ford Explorer and the pump was clicking past $80,” said Mr. Strom, a 66-year-old retired manager of a Chevrolet dealership.

Previous spikes in sales of smaller cars were often a result of consumers trading down during tough economic conditions or gas-price increases. When the economy improved or fuel prices dropped again  as they did after the oil-price shocks in the 1970s eased  buyers invariably went back to bigger vehicles.

But with oil prices expected to remain high for years, auto industry executives are seeing a turning point.

“The era of the truck-based large S.U.V.’s is over,” said Michael Jackson, chief executive of AutoNation, the nation’s largest auto retailer.

Sales of traditional S.U.V.’s are down more than 25 percent this year. In April, for example, sales of G.M.’s Chevrolet Tahoe fell 35 percent.

Full-size pickup sales have fallen more than 15 percent this year, with Ford’s industry-leading F-Series pickup dropping 27 percent in April alone. Sales of pickups, though, are expected to strengthen with the economy, because of their use as commercial vehicles.