Free enterprise isn't dead in America. At least not in Potomac, during the Kemper Open golf tournament.

Combine thousands of cars driven by golf fans and two dozen front lawns a few minutes walk from the Congressional Country Club and you have parking lots where there were none before, and a whirlwind exchange of cash.

Never mind that this is a community of lawyers and doctors, a community where houses can go for $500,000. Never mind that the turf the cars chew up is at all other times lovingly tended. There is big money to be made, at $5 a car.

"Every car represents a six-pack," said Scott Small, who by 10 a.m. yesterday had logged $850 in parked cars into the two-acre yard of his parents' house on Congressional Court, just a block off the club's fairways. So far, the closest thing to a mishap was an elderly man who almost backed his Cadillac into the pool.

In past years, charging people to park on one's lawn during the tournament was illegal, and authorities at times swooped down on offending households with misdemeanor summonses.

Some residents applauded attempts at enforcement, complaining to county officials that the neighborhood's green and open space was being turned into a parking lot.

But this year, as the result of pressure from those anxious to do busines, it is legal. The Montgomery County Council amended the zoning laws.

Today, homeowners paying a $25 fee--the take from five cars--can get a special zoning permit that allowed parking for 10 days--if "conducted in a safe manner." Twenty-three households obtained permits this year.

And business was humming yesterday, with cartels, price wars, dirty tricks, government regulation and entrepreneurial energy that people didn't know they had until they smelled the money.

"We have to get up at 6:30 in the morning and stay out 'til midnight to make sure all the drunks don't knock anything over," said Tim Casey, directing cars behind a house whose owner had fled to Colorado for the duration.

Five of Congressional Court's seven households were in business yesterday. El Dorados, Toyotas and an occasional Mercedes formed rows beneath dogwoods and by beds of iris. Cars were parked atilt on grass slopes, between shrubs, next to swimming pools and against wooden fences.

Many operators are sons and daughters of the houses' owners, together with friends. In the morning, they try to establish a common price, which everyone is supposed to honor. The more cars, the higher the fee. "It's just smart business practice to raise prices when demand goes up," says Small.

As the caravans arrive, workers with red flags and signs are stationed at the block's end to lure customers in, and attempts are made to distribute the automotive bounty evenly up and down the block. But the business can be rough-and-tumble, operators say, with the competition tearing down signs.

Operators learn skills useful in their larger business world--greeting their clients with a smile, keeping the smile when they're told that $5 is a rip-off, that at that price there ought to be paving and maybe someone should spin their wheels over the sod a bit just to get their money's worth.

They learn whether to accept travelers checks, what to do when a car blows out a radiator on the property, how to deal with the beer cans and trash some people leave behind and how to roll and reseed the tire-ravaged lawns to their parents' satisfaction.

In addition, they are occasionally invited to join in champagne picnics with the fans. And there are late-night parties with fellow entrepreneurs to celebrate the profitable day.

Montogomery County police officer Brad Graham, directing traffic at River Road and Bradley Boulevard, found the whole thing mystifying. "I just don't understand that someone with a half-million dollar house is going to let someone park in their lawn . . . ." he said. But "It's their land and they can do what they want with it."