Strollers and shoppers in Georgetown blinked in apparent disbelief one afternoon last week when a trolley clanged past on Wisconsin Avenue.

It was like a scene from yesteryear, when electric streetcars with open sides and wooden bench-like seats hauled fun seekers through Georgetown and along the Potomac palisades to the Glen Echo amusement park.

But the event in Georgetown was also a preview of tommorrow -- a demonstration trip of a gasoline-powered replica of a trolley that soon may carry passengers up and down Wisconsin Avenue and along M Street through Georgetown's commerical areas.

If it can raise about $10,000, the Business and Professional Association of Georgetown will operate the trolley throughout the summer, providing free rides to shoppers.

The idea, according to Richard McCooey, president of the business group and operator of the 1789 restaurant, is to encourage shoppers to visit all parts of commerical Georgetown and to cut down the neighborhood's monumental traffic tangles.

As the motorized trolley rounded the bend from the Four Seasons Hotel, its starting point for the afternoon's tour, Rae Koch reached above the driver's head and yanked a cord dangling from the roof.

"Clang! Clang! Clang! it resounded, for the moment making M Street look and sound like San Francisco's Powell Street, with its open-air cable cars.

"It's fun," Koch enthused. "It's just like being a kid again. It's like one of the trolleys we used to have in Baltimore."

True, the vehicle looked like the old trolleys, with wooden seats for 42 passengers and a carefully crafted oak interior reflecting the recaptured skills of the old-time carmaker. c

Only it really was not like the trolleys that ran in Baltimore, Washington or anywhere else. Georgetown's new trolley is not a trolley at all, but a gasoline-powered bus -- an old-fashioned body that moves on four rubber tires.

Washington's real trolleys were powered by electricity and ran on tracks embedded in the streets. Some of the tracks are still there, notably on some Georgetown side streets.

The last real trolleys that ran through Georgetown until early 1960 were streamlined and looked like buses. But in the early years of this century, there were open-bodied cars of the kind represented by the new motorized replica. The last of those open-air cars went out of service in 1937.

The replicas are manufactured in Decatur, Ill., and are owned by Trolley Tours, Inc., of Fort Lauderdale, Fla., which operates several of the vehicles in Florida. For the Georgetown merchants, the firm has offered a short-term lease with a later option to buy. Each vehicle cost $42,000.

The idea for running the Georgetown shuttle came from Carol Wright, executive director of the business association and operator of Crumpets, an ice-cream store.

"I saw four of them running in my little home town in Florida, Lake Wales, and decided if they could do it, why couldn't we?" said Wright.

For those interested in genuine trolley nostalgia, the idea of bringing back real streetcars to Georgetown is still alive.

A study financed by the U.S. Department of Transportation and administered by the city government has found such a prospect is feasible, if expensive. Anthony Rachal of the city's Department of Transportation said a further study of a permanent trolley system soon will be undertaken.