LOS ANGELES (AP) _ The timing seems a bit off. Just as the Persian Gulf crisis is again underlining America's dependence on foreign oil, U.S. automakers are introducing a road load of full-size cars.

Then there's the recession, seemingly custom-designed to wreck this year's sales. Mid-December figures released Wednesday showed car and light truck sales by major U.S. manufacturers fell 19 percent from mid-December a year ago.

Yearly sales figures are due Friday, and they're expected to drop by 4 percent to 14.2 million. Many analysts and auto industry executives are forecasting another 5-percent decline this year to 13.5 million vehicles.

''It's unfortunate that the industry's product cycle led to the introduction of full-size cars just as the recession and the Persian Gulf crisis hit,'' said Ronald Glantz, a Dean Witter Reynolds auto analyst in San Francisco.

''But the fact of the matter is, there's no point in delaying full-size cars once you have them ready for production,'' Glantz said Thursday.

Among the new full-size cars at Thursday's preview of the Greater Los Angeles Auto Show, which opens Saturday and ends Jan. 13, were Ford's Crown Victoria and Mercury's Grand Marquis. Each of those has gas mileage improved by 1.5 miles per gallon, from 17 in the city and 24 on the highway last year, which should help sales, Glantz noted.

Still, in the current atmosphere, there is something a bit jarring about a car like Buick's massive Roadmaster.

The luxury V-8 Roadmaster, a re-introduction of a name made famous in the '30s, '40s and '50s on Buick's ''porthole''-dotted sedan, comes out this winter as an eight-passenger wagon, followed by a six-passenger sedan in the spring, priced in the mid-$20,000 range, between the Le Sabre and Park Avenue.

Just how big is it? The Park Avenue can haul a trailer weighing up to 3,000 pounds. The Roadmaster sedan, with a 5.7-liter engine, pulls 5,000 pounds.

''With the rising gas prices and the situation in the Persian Gulf, it's hard to say what will happen,'' said Bob Coletta, Buick's assistant general sales and service manager.

He said Buick increased its market share from 5.5 percent to 5.8 percent in 1990. The carmaker says its realistic goal is 8 percent by the middle of the decade because it is carefully listening to what its buyers want - ''premium American motor cars'' and ''muscular grace.''

At 16 mpg in the city and 25 mpg on the road, the Roadmaster compares favorably with minivans that can carry as many passengers, Coletta noted.

''They're definitely large cars, but they're still fuel-efficient cars,'' Coletta said.

Chevrolet General Manager J.C. Perkins showed off other vehicles including a new $20,000 Caprice LTZ loaded with police car-style suspension, tires and gauges, priced with the adventurous young buyer - or police themselves - in mind.

The real sales star was the low-priced, high-mileage Geo - now the fourth biggest selling import line behind Toyota, Honda and Nissan. Geo's three cars and one sport-utility vehicle accounted for about a quarter of Chevrolet's total sales of more than 1.3 million last year, he said.

''That's no small accomplishment in today's marketplace,'' Perkins said.

He said nothing's certain these days, given the uncertain U.S. economy and the possibility of war in the Middle East in the next two weeks.

''The reason sales of full-size cars are poor is not so much the situation in the Persian Gulf as the fact that you don't stop off to buy a car on the way to the unemployment office,'' Glantz said.