Lenn Koneczny knows of a good auto mechanic near Vienna. "Customers say he . . . is very reasonable and he always guarantees his work," Koneczny said. But he wouldn't take his car to him -- in fact, Koneczny has been trying to shut him down for months.

Koneczny, a Fairfax County zoning enforcement supervisor, says the repair shop is one of many run illegally out of private homes in residential areas. But in this case, as in many others, he has been unable to prove it. "We've been refused entry" to the two-car garage used as a shop, he said. "We're not there to see the money transaction take place at all."

Frustrated by the difficulty of proving such cases, county officials are proposing to ban certain major auto repairs in residential neighborhoods, whether done for profit or on one's own vehicle.

Critics charge that the proposed zoning amendment would force car collectors and others who do their own auto repairs to patronize expensive commercial garages. But the amendment's supporters say few home mechanics can perform the complex repairs the measure would forbid, so only those running illegal repair shops would be affected.

"We're trying to give our zoning inspectors a better tool for cracking down. It is currently very difficult to prove a case unless you have a direct exchange of funds," said Dana Kaufman, administrative aide to Supervisor Joseph Alexander (D-Lee), who proposed the plan. "We're trying to make sure it is not a problem for the average homeowner who is saving money by doing minor repairs on a vehicle. We're not sending out a goon squad of inspectors to peer in people's garages."

"It's unenforceable, it's ludicrous and it's certainly a case of overregulation," said Planning Commissioner John Thillman, who was on the short end of the commission's 8-to-2 vote endorsing the proposed amendment. "It ought to be, you can do any of those repairs you want in your own garage with the door closed. If no one else can see it, it's not their problem. I think it's just a ridiculous ordinance."

The proposed amendment would forbid "major" repair or restoration work -- including transmission and drive train repair, major body work, major paint jobs, welding and machine shop work -- in residential areas, whether the work was to be performed indoors or outside. It also would ban some kinds of equipment, including painting booths, in-ground hydraulic lifts, in-ground oil pits, front-end alignment machines and engine hoists.

It would allow specified auto maintenance such as repair or replacement of mufflers, brakes, shock absorbers, carburetors, hoses, fluids and filters, as well as minor painting and rust repair work. If performed outdoors, such work would have to be completed within 72 hours.

"This, I think, permits 99.9 percent of the type work that the average Joe Blow will do on a car," said Planning Commissioner William Lockwood, who supports the amendment.

"There was never any intention of preventing the average homeowner from changing his oil or water on his car to save money," Alexander said. "It was to eliminate the commercial work . . . . The source of it were the many civic associations . . . that have complained."

Bob Lowery, president of the Jefferson Manor Civic Association near Alexandria, said his neighborhood's narrow streets are often lined with vehicles in various stages of repair. "It's nothing to see them pull the motor out of the car right on the street," he said. " . . . This goes on every day . . . . It's definitely unsightly. Sometimes there are cars up on blocks for weeks and weeks and weeks."

Antique and race car collectors say the proposed amendment could make their hobby prohibitively expensive, and are organizing to defeat or modify it.

Carol Mason, whose family collects classic MG sports cars at its home in Chantilly, said, "None of us have any objection to an enforceable amendment to keep junk yards out of neighborhoods . . . {but} we would like an exception for the hobbyist . . . . They're throwing out the baby with the bathwater."

Steve Gable, a Fairfax City area resident who owns two 1978 Oldsmobiles -- not classics -- worries that the ordinance might limit repairs he sometimes makes on his older cars. "It takes a lot of work to keep them going," he said.

The county board is to consider the proposal at 2 p.m. Feb. 8.