What's bad for General Motors Corp. is good for Jim Gauntlett, especially if "bad" means declining car sales.

Gauntlett, president of the Team Car Care Warehouse chain in Capitol Heights, is in the $27.6 billion automotive aftermarket business.

That means he sells floor mats and transmission parts, side-view mirrors and super-sophisticated gearboxes -- almost anything customers can use to make old cars run and look like new.

Gauntlett, former vice president of merchandising for Landover-based Trak Auto Corp., said he has learned in his 15 years of auto parts sales that "whenever new car sales go down, the parts business goes up."

"It's not that I want anything to happen to the economy," Gauntlett said. "But people who buy new cars tend to go to their dealers for parts and accessories while the cars are still new."

People who hold onto their cars longer -- during a recession or some other economic downturn -- often turn to parts stores to maintain their machines, Gauntlett said.

Auto industry analysts agree. They say the psychology and economics of long-term car and truck ownership favor the aftermarket stores, so-called because they sell products used to improve or repair a vehicle after it has been sold by a dealer.

People who want a new vehicle, but can't afford one, frequently dress up what they have, with new floor mats, new body-striping, new wheel covers, fancy steering wheels and gearshift handles. Analysts call it "the feel-good principle," the same force that drove some buyers to Porsches, BMWs, Corvettes, Firebirds and Thunderbirds in the first place.

And do-it-yourselfers seem to flourish in tough economic times, experts say, changing their own oil and air filters, installing their own car stereos and, particularly in the case of older cars and trucks, attempting more ambitious repairs, such as valve jobs on engines.

"You can show dozens of analyses that demonstrate the countercyclical nature of the automotive aftermarket," said Henry P. Allesio, president of Easton Consultants Inc., a marketing and management consultant firm in Hopkinton, Me. "You have more aftermarket sales in a soft car market."

So a prediction that total U.S. car and truck sales next year will fall at least 5 percent below the 1987 level of 15 million units is good news, aftermarket industry executives and analysts said. And speculation that the economy could slide into a recession in 1988-89 is even better news, they said.

"A recession would be good for my side of the business, even though I hate to use the word recession," Gauntlett said.

Belief in the ability of the auto parts business to resist recession is bringing in a horde of new players, including Gauntlett's barely one-year-old outfit, and forcing car dealerships to place heavier emphasis on their parts operations.

Team Car Care Warehouse, which has three stores in Capitol Hill, Glen Burnie and Oxon Hill, is taking on Trak Auto, Pep Boys and other supermarket-type auto parts stores in a bid for a share of the $27.6 billion a year that Americans now spend on auto parts and accessories.

Excluding petroleum and chemical products, and using current dollars, that $27.6 billion is more than double the $12.8 billion spent nationally on parts and services in 1977, according to Find/SVP, a New York-based firm specializing in market research for corporate clients. Using the same criteria, Find/SVP estimates that the national automotive aftermarket will double to $55 billion a year by 1995.

Comparable and accurate local figures are hard to find because of the wide array of auto parts stores here, most of which are privately owned. But the Washington metropolitan area is America's fourth-largest market in terms of new-vehicle sales, with $1.2 billion in 1986, according to a report by Auto Age, a national dealer business magazine.

New cars become ripe for aftermarket products within months of being on the road, according to Auto Age editors. Auto dealers tend to reap the benefits of aftermarket sales in that honeymoon period, the first year of new-vehicle ownership, the editors said.

For example, the Washington area's 24 largest dealers sold $154.8 million in parts, accessories and services in 1986, the magazine said. Of that group, Lustine Chevrolet of Hyattsville moved the most parts, with sales of $29.5 million, the Auto Age report said.

New car dealers have not always been interested in the aftermarket, Allesio said. Before the oil crises of the 1970s and before the 1981-1982 recession, dealers usually relegated parts and services to what they called the "back end" of their business. The "front end," the sale of new vehicles, generally received most of the dealers' attention.

But with inventory backing up in the "front end" because of declining car sales, many dealers began giving the "back end" more prominence. And despite Lustine Chevrolet's performance, the dealers of foreign cars and trucks still take the lead over most domestic dealers in selling parts and accessories, Allesio said.

"Foreign auto dealers have done a consistently better job of retaining aftermarket share because their manufacturers have always regarded parts and services as being an integral part of the new car sale," Allesio said. Until recently, "domestic car dealers have had something of an attitudinal problem. They just never saw the back end as being a key part of the sale," he said.

There is grudging agreement with that assessment among some U.S. auto makers, who have launched campaigns to get their dealers to move the back end up front. Ford Motor Co., for example, is experimenting with the concept of setting up separate, supermarket-type auto parts stores in many of its new car outlets. The idea is to replace the traditional, often grimy, over-the-counter parts operations with attractive retail stores run by friendly, knowledgeable employes.

But what still is a concept at Ford is functional reality at Toyota Motor Corp. Witness the aftermarket shop at Tysons Toyota on Leesburg Pike in Vienna.

"If I had to do it over again, I'd make it twice as big," said Frank VanDoren, who runs the Tysons Toyota parts center. It is a brightly lit and colored place, with parts neatly arranged on shelves. Toyota jackets and other apparel are available, as well as auto parts and tools. Parts are tracked by computer, instead of by the often confusing catalogues found in many dealership parts operations.

"We've had a steady increase in traffic since we opened in December 1986," VanDoren said. Tysons Toyota "always had a strong parts operation," but the company decided to beef up that segment of its business as a possible hedge against slow vehicle sales, VanDoren said.

Toyota Motor Corp. helped by making Tysons Toyota one of 14 pilot dealers nationwide to open Toyota Parts Centers. The objective is to hold on to the nation's 3.5 million Toyota vehicle owners by providing them with all of the parts and accessories they might be tempted to buy at other stores, Toyota officials said.

"We see a significant market out there," a Toyota Motor Corp. spokesman said. "More than 44 percent of our people are do-it-yourselfers."

Does that mean Toyota is going after Trak Auto, which sells auto parts at discount prices nationally and earned $1.3 million on sales of $183.7 million in 1986? "Yes and no," the Toyota spokesman said. "If our people are shopping at Trak, we're going after them. We're going after our own."

Robert M. Haft, president of Trak Auto, said he welcomes the competition. "The good thing about retailing is that customers vote everyday by shopping, and they've been voting for Trak by coming into our stores," Haft said.

Trak , which started business in 1979, has 80 stores in its "eastern region," which includes metropolitan areas surrounding Washington, Baltimore and Richmond. By the end of 1988, Trak expects to have 100 stores in the region, Haft said.

That projected growth, plus an expected $200 million in sales for 1987, "is a testament" to consumer support for Trak's marketing concept of offering brand-name products at discounted prices, Haft said.

For example, Trak sells popular Champion spark plugs at 51 percent less than their regular retail price. The company also offers Motorcraft (Ford Motor), Bendix, Bosch and other brand-name parts at prices ranging from 30 percent to 35 percent below their normal retail costs, Haft said. The company turns a profit on volume, he said.

Newcomers will have a hard time beating those prices, said Haft. And the auto dealers? "They can't match our prices."

Indeed, no one expects dealerships, which occupy about 21 percent of the automotive aftermarket, to take away the majority of that business. "Dealers can make $1,000, with few headaches, on the sale of a car. They can make $2.25, with lots of administrative headaches, on the sale of an auto part," Allesio said.

But with nearly 140 million cars on the road, the aftermarket is bound to remain big time for years to come, the analysts said. The key growth areas in the aftermarket will be auto sound products -- car stereos, for example. Electrical, electronic and ignition products also will play major roles in the growth of that market between now and 1995, according to Find/SVP.

Even telephone firms will get a bite of the action. For example, sales of cellular telephones for auto use are expected to grow by nearly 21 percent a year between now and 1995, according to a Find/SVP report, "The Automotive Aftermarket."

But what seems to be a hot market for entrepreneurs is not necessarily a hot market for investors, Allesio warned.

"If you sit and listen to everything you read about the automotive aftermarket in the trade press, you can wind up making some bad investments," Allesio said, noting that aftermarket sales are rising much faster than profits.

"You've got a lot of aftermarket companies out there building and opening new stores to gain sales growth," Allesio said. The stores are getting the sales, "but the overhead is often horrendous," he said.

Gauntlett of Team Car Care Warehouse, a wholly owned subsidiary of G&M Performance Parts of Capitol Heights, is undaunted. "We're building a giant-killer, a one-stop shopping place where you can get what you want when you want it in the quantity and with the quality you want it," he said.

"What we have are three-in-one stores -- one store selling replacement parts, another selling accessories and another selling performance auto parts {for auto-racing enthusiasts}, all under one roof," Gauntlett said. TCCW's parts usually will cost more than those carried by the discount parts houses, but "our quality is better," he said.

Will it work?

"Yeah," said Gauntlett. "We plan to open three more stores in the Washington area by the spring of next year.