Put four wheels on a trampoline and you have a low-cost imitation of America`s sports car.

Add a bucket seat with side bolsters so snug the seat should be offered with a month`s worth of Weight Watchers frozen entrees to ensure you fit reasonably well.

Finally, hitch that trampoline to a 5.7-liter, 245-horsepower engine teamed with a 4-speed automatic, and you have a fairly apt description of the 1991 Chevrolet Corvette.

For the power, you sacrifice room and comfort and ride and handling.

But then add a convertible top, and the gripes and complaints and hardship of squeezing behind the wheel of a plastic-shelled rocket become but a distant memory.

A `Vette convertible isn`t hard to take. It has a manually operated top, but it`s relatively easy to bend and fold without spindling or mutilating your hands or fingers. And the canvass hides neatly away under a plastic tonneau cover.

The `Vette ragtop is a vehicle to be seen in, providing no one sees what you have to do to get in or out of the low-slung machine or how you walk for several minutes after you do.

Wind slams your jowls in a typical convertible. Gentle winds caress your checks in a $40,000 `Vette drop top.

There was a switch on the center console that allowed us to move from touring to sport to performance suspension settings. Actually, we were hard- pressed to notice any difference among the three. The notches on the dial could be labeled stiff-stiffer-stiffest.

To complement the power, anti-lock brakes are standard. As an added safety measure, a driver`s-side air bag is standard, too.

To ensure you prompt, envious stares or glares, Chevy offers the `Vette convertible with a turquoise metallic finish. No matter from what angle you gaze at the car or what the light happens to be at the time, turquoise metallic sure looks green. And it sure looks very nice.

The convertible starts at $38,770. The test car added a host of options including power driver`s seat for $305; black leather sport bucket seats for $1,100; three-way suspension for $1,695; engine oil cooler for $50; low tire- pressure warning system for $325; Delco-Bose AM/FM stereo with cassette, compact disc player and digital clock for $396; and a bunch of other assorted goodies that ran the sticker to $44,224. You also must add a $550 freight charge.

Considering `Vettes are selling like sand in the desert, you should be able to garner a significant discount.