Detroit is the place people usually go to report on the problems of the U.S. auto industry, but you don't have to leave Washington to gain insight on the state of the car business.

In Detroit you can find idle factories, empty smokestacks, unsold cars and unemployed auto workers--all evidence of the difficulties the industry faces.

Here in Washington there are no signs of Detroit's suffering in the glistening showroom strip at Tysons Corner, the vast lots of the Montgomery Auto Sales Park or the sprawling Marlow Heights dealer district.

There you will find the good news from Detroit--the most exciting batch of new cars the American auto industry has turned out in a decade, an extraordinary top-to-bottom lineup of well-designed new products.

The new Corvette is the best sports car Detroit has ever built and the down-sized General Motors A-cars prove family cars don't have to be gas-guzzling behemoths. Ford's wind-cheating new Thunderbird is a bold innovation in aerodynamics and its wind-in-the-face Mustang convertible is a bolder attempt to recapture the youth market. Chrysler has revived the ragtop rage with its K-car convertibles, recaptured the spirit of the '60s with its Shelby Charger and soon will revolutionize the van business with its new mini-truck. Even the Franco-American Alliance is a smash that has boosted American Motors' sales by 175 percent.

Some car buyers are willing to wait in line and pay a premium over the sticker price for a Corvette, a Mustang convertible or a much-coveted Chrysler.

But lots of potential car buyers are reluctant and the explanation for their hesitation may be seen more easily in Washington than in Detroit: Hang around the National Highway Traffic Safety Administration or the Environmental Protection Agency some day and read the recall notices. Talk to the Federal Trade Commission, the Better Business Bureau or Maryland consumer protection officials about abusive auto sales practices.

If you could get a Purple Heart for shooting yourself in the foot, lots of executives in Detroit would be wearing a chestful of medals.

Take the new Mustang convertible. It's so new that most people have never even seen one, but already it's being called back. On Friday Ford disclosed a little problem with the $13,000 Mustang convertible: sometimes when you put the top down, the frame rips holes in the fabric.

Ford's prompt promise to fix the problem and replace the entire top if it tears is reassuring, but isn't this the outfit that advertises "Quality is Job One"?

One recall notice and a couple of hundred torn convertible tops can wipe out millions of dollars worth of Ford's corporate image building.

And Ford has had a good year compared with General Motors. GM's foibles are the chief reason why there have been almost as many recall notices issued in the first three months of 1983 as in all of last year.

Though both NHTSA and EPA have been accused of bending over backwards to protect the industries they are supposed to regulate, the two agencies so far this year have been forced to issue 2,395,000 recall notices, compared with 2.7 million in all of 1982. That doesn't count the as many as 5 million GM cars with what is still considered a potential hazard of the rear axle falling off.

In the last few weeks General Motors has recalled 527,000 1978 models for exessive air pollution, 240,000 compact X-cars for brake problems and 491,000 Chevettes and T-cars because a fuel line can come loose causing an engine fire.

If the fire hazard weren't enough to frighten away buyers, GM admits there is a shortage of the $1 part needed to cure the fuel line problem. One Washington couple is suing because, they say, their Chevette burned up two days after a dealer told them he didn't have the part to perform the recall repairs.

On the same day that story came out, NHTSA disclosed it is investigating at least 160 fires involving the Ford Escort and Mercury Lynx, the best-selling car in its class.

All these recalls have put Detroit "very much on the defensive as far as quality" said Arvid Jouppi, a well-known auto industry analyst. "The recalls sharpen a customer's perceptions or feeling about quality," Jouppi told UPI. The potential buyer who has "been worrying about other things" is "forced back into thinking about quality" he said. "It plays right into the hands of the imports."

If manufacturing defects weren't enough, there is growing evidence that the difficult market is encouraging some auto dealers to revert to sleazy sales practices. Bait-and-switch tactics, "mandatory options" and misleading advertising have drawn recent complaints from the FTC and state regulators. Even the Better Business Bureau--never known as a nasty watchdog--has warned local dealers to clean up their act.

Maryland officials have sent out a steady stream of warnings in recent months to dealers whose ads appear misleading, yet new nuances keep coming up. Among the latest is the dealer who advertises "your monthly cost" of a popular subcompact is less than $100.

"Your monthly cost," of course, has nothing to do with your monthly payment. The "monthly cost" turns out to be the estimated monthly depreciation of the car if you keep it four years and then trade it in for the price promised by the dealer. Neither interest nor taxes is included.

Fortunately for Detroit, dubious sales practices are not limited to domestic dealers. The Maryland attorney general is negotiating a deal to force Toyota dealers in Maryland, Virginia and neighboring states to pay back $4.8 million to customers who allegedly paid inflated prices for 1980 Toyotas.

In the biggest antitrust case the state has ever brought, attorney general Stephen Sachs says Toyota buyers were forced to pay for extras they didn't want including undercoating, rust-proofing, interior protection and paint sealant. (Such add-ons are sometimes known as "the sandwich," a salesman once explained. "You put the undercoating on the bottom, the paint sealant on top and a lot of baloney in the middle.")

It ought to be obvious from the depressed car sales figures that auto buyers are tired of baloney. They're fed up with burnt-up engines, undercooked engineering and half-baked cars. Detroit had better get cooking.