Asian automakers, which offer a wider range of more fuel-efficient vehicles, continued to post sales and market share gains.

With high gasoline (petrol) prices eating away at sales of trucks and large SUVs, Ford Motor Co. took the offensive Thursday by offering customers free gasoline for a year along with zero percent financing on vehicle purchases.

The automaker offered customers a gift card for 1,000 dollars to be used on gasoline which it estimates will cover most bills through the end of the year.

Ford's "Drive on Us" incentive follows a gasoline "price-cap" deal rival General Motors Corp. offered some customers in Florida and California. Car buyers were offered pre-paid gasoline cards that would compensate them if pump prices exceeded 1.99 dollars per gallon.

That deal did little to boost GM sales, however.

GM posted Thursday a 16 percent decline in demand in May from a year ago, ending at 345,157 units. Passenger car demand was lower by 19 percent at 129,905 units, while truck sales were off by 13 percent to 215,252 units.

GM's lack of fresh products on the car side of the business added to the pain, the automaker said.

"This was a challenging month for us," Paul Ballew, GM's director of global market and industry analysis, told reporters on a conference call.

He said demand for some traditional truck-based SUVs, particularly the Chevrolet Trailblazer and GMC Envoy, were running at nearly half the pace of a year ago.

"These categories were experiencing significant downward pressure."

The story was similar at Ford, where sales were off 1.9 percent from May 2005 at 278,546, after strong car sales were unable to offset a steep drop in demand for trucks and SUVs.

Truck sales fell 6.6 percent to 170,298 units while passenger car sales climbed 6.4 percent to 108,248 on the continued success of the Ford Fusion, Mercury Milan and Lincoln Zephyr sedans, as well as the Ford Mustang and Focus.