Looking up at imposing facade of the Buick-Cadillac agency here, you wonder what business philosophy guides it.

Is it the selling-Frigidaires-to-Eskimos school?

Maybe the screen-door-for-submarines principle?

Perhaps some variant of the old coals-to-Newcastle doctrine?

Or can it be some kind of mercantile hari-kari?

But when you enter, you find it is none of these. In fact, the 64-year-old Yanase & Co. turns a very tidy yen selling big American gas guzzlers in this lair of the gasoline-stretching small cars and of $1.90-a-gallon fuel.

Through what prodigy of salesmanship is this achieved?

"We emphasize four points;" says Robert M. Ohta, Yanase's deputy general manager, speaking in the musical cadences of his native Seattle (he enjoys dual citizenship):

Safety. "We point to the more rigid metal, the thicker doors, the extra power to overtake other cars in a tight spot."

Easy driving.

Comfortable ride.

Prestige. "That's the big point. Many of our customers are men who want cars that say 'I'm the owner of a Cadillac, the owner of a Buick.' In addition, we stress the recent improvements in the price of U.S. cars over here and the coming new smaller cars." Some tax advantages can result from bying a big car for business reasons, he added.

He also said that in competing here, U.S. cars face these drawbacks:

Quality deficiencies, or sloppy workmanship. "The Japanese regard a car as an investment and a luxury, where an American regards it as a kind of tool for making a living. American buyers aren't bothered much by a misalignment of chrome or scratches in the paint. But here, people care a great deal. We often have to re-do paint jobs, even on Cadillacs, and that's very expensive."

Price. A 1979 Buick Skylark custom coupe or sedan, a middle-income car in the States, cost 3.18 million yen, or $14,326, here this has turned slightly favorable for Yanase because 360 yen once were needed to equal a dollar, but now only 220 are. Yet that price is 100 percent higher than the same car, the bottom of the Buick line, would cost in the States "loaded" with optional equipment.

Car size. The new smaller "X" line of U.S.-built General Motors Corp. from-wheel-drive cars may remedy this, Japanese salesmen hope.

Is something missing from the list? Here, where every drop of oil must be imported, isn't the U.S. car's miles-per-gallon ratio a liability?

No, says Ohta. "People who can afford these expensive cars don't have to worry about gasoline costs, although smaller car owners here are much more cautious about gasoline."

Yanase is also the agency here for some European-made car: Mercedes-Benz, Audi and Volkswagen. And outside Tokyo it sells Chevrolets.

At Yanase, the European cars sell better than the U.S. ones, although both share a minute slice [imported cars are 1.3 percent of total sales] of the Japanese market. The European cars have fewer of the imperfections in workmanship that rankle finicky Japanese car buyerss, said Yanase's director and general manager, Masaya Cinda.

"We have to do five or six times more work on our American cars," he said." An expert from the U.S. told us: It isn't necessary to do all of the this predelivery conditioning. You overservice.' But we must. Often chrome isn't in line from the door to the fender and we have to do it over.

"That means that we have to paint over the spot."

He pointed to a big blob of metal along the bead of a weld and a bumpy finish on the paint, as well as on the underlying metal, of a Skylark door frame.

We'd have to file this down and paint it again. On the European-made cars, you don't find that. That's why the Japanese like European cars . . ."

"Japanese have a strong belief that German products are very good technically, in engineering," Ohta said. "Even if the price is very high on a Mercedes, they'll buy it."

U.S. cars have a good reputation of maintenace, he conceded. "They're easy to care for. European cars have more complex engines. No, there's nothing against American cars in that respect."

U.S. car sales here have brightened considerably. Although the trend had been stadily downward, they rose by 30 percent during the first three months of this year compared to the previous quarter.

"That's because the price went down twice, once in March of last year and once in November," said Cinda. But even that increase trails 50 percent rises for other imports.

Last year, in a gesture toward freer trade, the Japanese removed the import duty. Along with the lower exchange rate for the dollar, that has helped to reduce the price.

The biggest recent year for U.S. car sales by all Japanese dealers was 1975, when 16,730 were sold. By last year, that figure had sagged to 13,943. But Yanase's share of the total GM market in Japan is better than 18 percent.

Other factors still cause a vast difference between the U.S. and Japanese prices. One is a 20 percent commodity tax on all autos, even those made in Japan. Ocean freight and special destination charges add more. Japanese law requires extra equipment [such as emission control systems, heat shields, emergency lights and amber lenses in the turning signals], and each car must be tested before it leaves the States.

Another price-booster is the Japanese penchant for options, said Ohta. "They like to get all of the equipment possible."

Gleaming in a corner of the showroom is a dazzling cream-color Skyhawk, a two-seater sports car. "Who in Japan could buy a car like that?" you ask.

"Oh, a movie star -- or maybe some girls from the Ginza," said Cinda with a smile. CAPTION: Picture, Robert Ohta (left), and Masaya Cinda.