Do you know the WORST ENEMY your car's finish can have?

YOU!

A 30-second commercial opening with that admonition and trumpeting the dangers of washing your own car will begin airing on various news and weather shows May 1.

Is it true? Have millions of Americans been causing bodily harm every time they wash their beloved wheels?

The $300,000 campaign -- paid for by the carwash industry -- doesn't come right out and say so, but their ad does declare that "University research has proven handwashing . . . plus insufficient volumes of water from garden hoses . . . inadequate home detergent products . . . can gouge the paint up to one-tenth its thickness."

The emphasis should be on can. The study, conducted under a $100,000 grant to the University of Texas at Arlington, substantiated an earlier study done for Mercedes-Benz, according to Lou Kuhn, a spokesman for the International Carwash Association/National Carwash Council.

"The study also showed professional washes to be virtually harmless to cars," says Kuhn, "otherwise we wouldn't have gone with the study in the ad campaign."

Civil engineering professor Johnnie Matthys, who conducted the University of Texas tests, notes that paint panels -- not actual cars -- supplied by auto manufacturers were tested. "The panels we ran through a mock-up car wash suffered less damage in terms of gloss loss and scratching than the panels we washed using five different handwashing techniques.

"That does not," he stresses, "mean it is necessarily true for all handwashing techniques or for all automatic carwash techniques." groups generally view professional carwashes favorably -- while noting that they are more expensive than doing it yourself -- and list a number of benefits of going to the pros, among them: easy, thorough washing of the car's undercarriage; effortless application of a sealer wax for the car's finish, and rust inhibitor for the car's underside and other potential rust areas.

A note to consumers who complain that including the wax spray option with an automatic wash fogs or dulls their windshields: The waxy film can be removed from the windshield with a solution of ammonia and water. Says one carwash manager: "Most places will do the job for you when your car comes out from the wash. No problem."

If you want to have a clean car and save money -- complete carwashes in this area, including wax spray, rust inhibitor and underwash, generally run $5-$10 -- or if you enjoy washing and waxing your own car, some reminders:

Wash and wax your car at least twice a year. If you live in an area where salt and chemicals are used to clear icy, winter roads, or near industrial areas where there is excessive smoke, other noxious fumes or corrosive chemicals, or if you park your car outdoors, it should be washed and waxed frequently.

When washing your car, inspect it for scratches, chipped paint and rust spots. Prevention or early care of rust is considerably less expensive and time-consuming than after it has taken hold.

Don't forget the underside of your car. Caked mud, dried leaves and other debris should be removed regularly.

See that the drain holes in the bottom of the body panels and doors are kept open, to prevent rust on the inside.

Be sure that cloths and sponges are clean. Grit on any material used to wash or wipe off the body can act as sandpaper.

The most important cleaning agent for your car is water. You do not, say the experts, need to use any soap, although a mild liquid soap or commercial car soap may be used if desired.

Rubbing compound is used for removal of stains, scratches or smoothing the finish of a newly repainted car. It is relatively abrasive.

Polishing compound is used to remove mild spots and highlight the gloss of the finish. Although milder than rubbing compound, it also is abrasive.

Silicone provides a transparent, thin layer of film that deepens the color of the finish. Whoppers on Wheels

Burger King has hit the streets. Early this year the restaurant chain introduced the first of several mobile kitchens, all with the same fast-food menu as the stationery variety.

There currently are seven units (in Florida and California) with several more expected to be up and running early this summer. The mobile units are ideal, says a Burger King spokesman, for such places as colleges, hospitals, industrial parks, beaches and small towns whose populations fluctuate according to season.

Each of the $100,000 units is expected to yield $1 million annually in food sales, the same amount projected for the fixed facilities, which cost about $1 million to build.