It's been more than 20 years since Pontiac Division offered a Firebird convertible. Based upon the 1991 Firebird and Trans Am convertibles due in Indianapolis Pontiac dealerships next month, two decades plus has been too long to wait.

Pontiac's softtop Firebirds are the leanest, meanest-looking sets of wheels on the road.

The upscale Trans Am version of the convertible looks like it's going a zillion miles per hour just sitting still. And this life-in-the-fast-lane car will make even the most jaded turn their heads.

There is a certain sharklike look to the front end of a Trans Am, almost like a predator ready to bite anything in its path. When equipped with a 205-horsepower V-8, a speculative guess is the shark has pretty teeth.

"It's about the sexiest-looking car I've seen, " said Jim Mulvaney, general manager of Ed Martin Pontiac-Acura-GMC. "We've had excellent results with our (Pontiac) Sunbird convertible, and this one should do even better."

Pontiac's re-entry into the convertible market is aimed at a niche that the division says is expanding in a shrinking market. Statistics show that, while total car sales are down, the convertible segment has grown from 1 percent of total cars produced in 1988 to 2 percent in 1990.

"We've done so well with the Sunbird (convertible), " said Dave Wilkerson, general manager of Don Sisk Pontiac, "that a lot of people want to move up a notch in the marketplace and have a little more performance."

Pontiac believes that the convertible market will continue to grow during the 1990s. And with automobiles like a Trans Am softtop, the General Motors Corp. division feels that there is a decided enhancement of its reputation for performance.

That performance is based in large part on Pontiac offering three engines and two transmissions.

Available in the Firebird will be a standard 140-horsepower, 3.1-liter V-6 coupled to a four-speed automatic transmission. Optional will be a 170-horsepower, 5.0-liter V-8 coupled to either the four-speed automatic or a five-speed manual transmission.

The Trans Am model is the powerhouse package. It has a 205-horsepower, 5.0-liter V-8 and the five-speed manual gearbox included as standard equipment. The four-speed automatic transmission is an option with this car.

"I'm going to say that 90 percent of the convertibles we sell will be with the automatic, " Wilkerson said. "That's the percentage we sell with the regular (coupe) Firebirds."

There is a difference of opinion about engine choice, with Mulvaney believing that most Firebird buyers will opt for the 3.1-liter V-6.

"Insurance rates are pushing them into that, " he said. "I think they'll stay with the 3.1. It takes them out of that high-performance area, and that's where the high insurance cost is."

The Trans Am buyer has 205 horses under the hood, ready or not. But Wilkerson said, "I think even the person who buys the Firebird is going to opt more for the V-8."

One potentially questionable feature is that the top is manually operated instead of electric. It does, however, stow beneath a tonneau cover, leaving no visible signs of the top. Having it tucked completely out of sight contributes to the convertible's overall sleekness.

Both models carry the Firebird's Aero Package as standard equipment. The package includes fog lights, brake cooling ducts in the front fascia, and a distinctive side aero treatment.

The Trans Am also has functional hood louvers and air extractors for pulling heated air out from beneath the hood. For leather lovers, leather bucket seats are available for $780.

The base for the convertible is the Firebird coupe, with suitable bulkhead bracing incorporated to compensate for the lack of a steel roof. The roof is a stressed member of the coupe's body. Its removal results in flexing of the lower body unless this structure is bulwarked by additional bracing.

While convertibles traditionally sell better during the warmer months, Pontiac appar ently wants it s new convertible on stream ahead of the spring selling season. But Mulvaney said, "There's no reason to hurry. We may have them at the end of February, but March would do just as well."

Upon arrival, the price structuring doesn't look too bad. The manufacturer's suggested retail price is $19, 159 for the Firebird and $22, 980 for the Trans Am.

"That's a pretty marketable price, " Wilkerson said. "The Sunbird comes in around 17 ($17, 000) by the time you put the six-cylinder engine in it and other popular options. I'd say it's priced pretty good."

Buyers are expected to be in the 35 to 55 years of age bracket, individuals interested in sports oriented automobiles, and one who is driving or has driven an import. As a glamour car, the convertibles are being predicated as fun cars to drive, and they are going to be great for Pontiac Division's image.