Mark Hamill flirted with posthumous fame. Before the release of "Star Wars," he totalled his car in a crash that nearly cost him his life and did cost him his original face.

"It's unlikely that the pug-faced Mark Hamill who stars in "Corvette Summer" as Kenny Dantley, a scruffy Los Angeles car kid with a flair for design, would have been the first choice for Luke Skywalker. Luke's smooth angularity seems to have vanished, along with his aquiline. nose The planes in Hamill's face are now a little jagged and irregular, and Kenny could pass as Mick Jagger's runty kid brother.

The interesting thing is that Hamill's restored face suits the role of Kenny as well as his original suited Luke. Unfortunately, Hamill has been denied the opportunity to capitalize on his new appearance because "Corvette Summer" succumbs to structural damage that can't be repaired.

It comes as a keen disappointment when the movie's initially promising plot begins coughing, sputtering and misfiring incessantly. Writer-director Matthew Robbins and writer-producer Hal Barwood - who earned this bid for autonomy by writing the scripts of "The Sugarland Express." "The Bingo Long Traveling All-Stars and Motor Kings" and "MacArthur" - seem to have hit on a novel, appealing premise for a contemporary quest fable. Even as "Corvette Summer" degenerates into a shambles, you persist in thinking. "What a swell idea for a movie."

The most talented auto shop student in the senior class, Kenny salvages a wrecked Corvette Stingray from a car graveyard and oversees its restoration as a class project. The customized, kandy-kolored product in his special pride and joy. He imagines driving it straight to Detroit and asking for a job in the design department at General Motors.

But before Kenny can act on such engaging impulses, the car is stolen. The theft occurs on the very night the shop-class has choosen to display their handiwork up and down Van Nuys Boulevard, the principal cruising thoroughfare in the San Fernando Valley, wittily transformed into a boulevard of broken dreams.

Refusing to believe the police assumption that the car will be stripped for parts. Kenny posts notices around and gets a lead. Someone claims to have seen the Stingray in Las Vegas. Kenny sets off down the road determined to find and recover his dream car.

(This premise suggests entertaining symbolic possibilities. It's a pity they aren't exploited, because car freaks and movie freaks have definite affinities. Kenny could have been an emblem for struggling creative people in the movie business. Despite the systematic demand to shortchange or downgrade elder work as soon as the new line is ready to be marketed, both creators and audiences have a stubborn way of falling in love with certain models and trying to ensure the survival of such vintage favorites.)

These emotional undercurrents might have given the movie a peculiar intensity and authencity if Robbins and Barwood had kept the plot headed in credible, sympathetic directions. But the premise breaks down just at the point when it needs to be cleverly elaborated into a story.

That breakdown coincides with the introduction of a would-be adorable heroine, a baby-voiced waif who is headed for Vegas in hopes of catching on as a hooker. Annie Potts, the young actress who plays this numbskull (who had dubbed herself Venessa) posseses a piquantly photogenic face: but the character herself is excruciating. Robbins and Barwood may have had a contemporary equivalent of Fellini's Cabiria in mind, but they have failed to render her either believable or tolerable.

Vanessa undermines the characterization of Kenny, since Robbins and Barwood elect to have him panic ingenously in the face of her twittery, outspoken advances. Perhaps this approach to modern teen romance looked cute on paper, but it plays idiotically on screen. Kenny is interested at first because he seems such a tough, scroungy, self-sufficient kid. There's no reason for a lollipop trollop like Vanessa to throw him.

The more Robbins and Barwood struggle to rationalize this misbegotten romance, the more "Corvette Summer" begins to resemble a juvenile-division "Foul Play." Even the tone becomes similarly, foully facetious. The story develops a streak of gratuitous nastiness. Bit characters repeatedly demonstrate how corrupt heartland Americans are at heart. Sequences of strenuous knockabout farce are juxtaposed with bluntly menacing, vicious interludes. Typically, Kenny will save himself from being molested by Vanessa, spot his car passing by take after it and end up getting a beating for his pains. It's not much fun riding this merry-go-round.

It's possible that in their anxiety to direct and produce at last. Robbins and Barwood started throwing in everything they could think of to cinch the sale. Ultimately, the material is worked out in accord with low estimates of popular taste rather than the dynamics of real life or inspired dramatization. The compromise may not have been voluntary, but Robbins and Barwood disqualify themselves as Kenny's potential soulmates by selling out to the commercial devil in themselves.

Hamill and Potts might have been agreeable match. They give it a game try, but you don't envy them any more then you envy Chevy Chase and Goldie Hawn in "Foul Play." All of them do an awful lot of running without making the slightest headway.