Not everybody looking for a new car thinks first about cost or styling or fuel economy.

One client came to Al Jacobs--who is in the business of matching people with vehicles--hunting for a hatchback with easy access.

"He had an old dog who couldn't jump up very high," says Jacobs, president of Automotive Search Inc. of Bethesda, a year-old firm that aims--for a fee--to take the pain out of new-car buying. On most hatchbacks, the client had found, the rear door opens above the tail lights: too difficult a leap for his pet.

Jacobs consulted his library of car catalogs, cassette tapes and computer, which contains data on 200 American and foreign-made cars, and came up with an answer: a Swedish-built Saab. "The hatch goes all the way down to the bumper."

At today's high prices--average, about $10,000--it pays to know what you're doing, says Jacobs, with more than 350 new cars and 600 model variations to choose from. If you make a mistake, you'll probably have to live with it for awhile.

But to many people, buying a car is tedious. Many of Jacobs' clients are professionals, such as lawyers who say they can't spare the time--perhaps several days--for a proper search. "And," he says, "most people don't like to negotiate."

One Washington couple, perhaps not atypical, simply looked in the ads for a sale and then went out and bought a small two-door sedan at the advertised price (without so much as a test drive). They had minimized the shopping chore, but made an impractical choice for their needs. For one thing, they were remodeling and landscaping their home and quickly found they needed more trunk room for hauling.

For them--and others too busy or unwilling to visit a half-dozen or so dealerships--Jacobs offers two car-buying services:

For $12, he will mail you a four-page questionnaire in which you detail the type of vehicle you prefer (sedan? stationwagon?) and the characteristics most important to you (safety? fuel economy? trunk space?). "We rate your priorities, your driving habits." He will feed your answers to his computer, programmed to select three cars that most closely meet your specifications. These are the ones he suggests you test-drive.

For $175, he will guide you virtually by the hand through the whole car-buying process, which includes selling your old car. You get the computer search, an in-person or phone interview, and Jacobs will negotiate himself with the dealer--at a better price, he expects, than you can get. He will even test-drive your choice before you accept it and--to commemorate the event--plunk a bottle of champagne in the front seat (his house brand, Chateau L'Auto). "I'm on retainer as your representative."

Years ago, says Jacobs, when houses sold for $5,000 or $10,000, "you didn't need a broker." But as prices grew, home buyers sought a broker's expertise. That is the kind of help he sees a need for now with cars so costly.

At times, Jacobs says, he feels like an "auto psychologist."

"You get clients who have read the ads. But when you talk to them, you find out that's not what they really want." For example, "Divorced men in their 40s and 50s show up wanting a sports car. I tell them they want a car where they won't look ridiculous climbing out of it."

A large percentage come to him with their minds made up. "People read Japanese cars are superior and say, 'I want a Honda or a Datsun' . . . I will play the devil's advocate." For example, he shows them the price difference between Detroit models and foreign imports. The demand is high for Japanese makes, he says, so they tend to cost more.

One woman who preferred a Japanese car felt that, since she worked for the American steel industry, she should buy a home brand. Jacobs helped her find a native equivalent to the Honda: the new Pontiac 6000, an intermediate-sized front-wheel drive sedan with good mileage.

One client had established a price with the salesperson. After comparing prices elsewhere, he went back, but they wanted $250 more. In the business, says Jacobs, "we call that a 'low-ball' "--the salesperson offers a price that can't be beat by other dealers, but later claims a mistake has been made or the boss won't agree to the figure.

"We went to another dealership and negotiated for $200 less than the first price."

At 35, Jacobs has been buying and selling cars in the area for 12 years, most recently as a wholesale broker of used cars. He is an arbitrator for the Better Business Bureau and teaches an Open University course, "Everything You've Always Wanted To Know About Buying a Car, but Didn't Know Who To Ask."

"I eat, sleep and drink cars," he says. "I read everything available on cars. I test-drive cars almost every weekend."

His firm is on hand at delivery day for a final test drive to check for defects. Among possibilities: "rattles, squeaks, windshield wipers that may not work at low speed, loose carpeting, paint scratches, interior lights that don't work. Anything man-made is going to have problems."

Automotive Search, says Jacobs, is not affiliated with any automobile manufacturer or dealer, nor does it get commissions from them. "We receive no money for referrals to individual dealerships, nor for encouraging or inducing the sale or purchase of a specific make or model."

Most dealers, he says, have been willing to work with him. "It's all plus business for them." The fact that he buys 25 to 30 cars a month, he says, helps get him price breaks.

Jacobs insists that his clients test-drive a car before making a final decision, and he will make the appointment with the dealer. One reason: Not everybody fits into every car. When one woman, at 4 feet, 11 inches, climbed into the car of her dreams, she found she couldn't see over the dashboard.

What does Jacobs, the car expert, drive? At the moment, he and his wife share a 1980 Cadillac, a new Datsun 280ZX and a replica of an MG roadster. But the car of his dreams?

"The Avanti."

Introduced by Studebaker in 1962--a "smash" hit, says Motor Trend magazine--the stylish sedan is now handbuilt to almost the same design in South Bend, Ind. About 200 customers a year pay the $23,000 selling price.

Its sleek look, says Jacobs, is timeless. "Because of my business, I like to be seen out there."

For more information: Automotive Search Inc., 7315 Wisconsin Ave., Suite 415 North, Bethesda, Md. 20814. Phone, 652-0160.