Pontiac may be blackballed from the automotive fraternity.

The General Motors Corp. division did the unthinkable.

At a time when rebates, zero percent financing and $50 below invoicesales are the norm to sell cars, Pontiac went and lowered the price.

The subcompact Sunbird GT convertible wasn`t selling well in the 1989model year, a mere 3,009 copies for the 12 months of the model run.

Now 3,009 isn`t bad if you`re peddling Ferraris, Lamborghinis, Rolls-Royces or even used DeLoreans. But the bean counters don`t take kindly to a3,009-unit car at a division that`s supposed to sell 700,000 vehicles a year. So Pontiac figured what the heck, it had nothing to lose. It dropped theconvertible from its top-of-the-line Sunbird GT performance model that startedjust shy of $18,000 for 1989 and brought the ragtop out on its base modelSunbird LE for 1990 with a sticker starting at $13,924.

That meant a $3,400 savings for those interested in a convertible.Consumers have taken advantage of it.

For the 1990 model year, sales of the cheaper LE convertible areapproaching 6,000 units and Pontiac expects 10,000 will be sold before themodel year closes Sept. 30.

Of course there was a factor besides price that helped Pontiac sell itsJ-body convertible. Chevrolet dropped its subcompact J-body Cavalier Z-24convertible for the 1990 model year in favor of bringing out a ragtop version of the compact L-body Beretta.

As an aside, Chevy may have outsmarted itself. The Beretta convertiblehas not been shipped to showrooms, and the project has been put on indefinite hold because the car doesn`t meet quality targets, sources said. Chevy has a$17,339 Camaro convertible and a $37,784 Corvette convertible, but nothinglower priced.

A convertible version of the mini Geo Metro is slated to appear in lateJune, but only 3,000 copies will be built and they will be sold in onlyIllinois, Michigan, Pennsylvania, New York, New Jersey, California, Texas,Florida and Hawaii. Estimated starting price: $10,000.

We test drove the `90 Sunbird LE convertible. After a few days daughter,No. 1 asked why a car with a base price of less than $14,000 could come with apush-button, power-operated top when the $53,000 Cadillac Allante(Transportation, Sunday, May 6) has a manual top that requires a freeweekend and a degree in physics to retract.

``We don`t understand why Cadillac even bothers selling the Allante, much less why it wastes your time and patience with a manual top,`` was the sage`s reply.

Despite the power top, the Sunbird convertible is priced $3,400 less than the former GT convertible because it is more frugally equipped than the GT.

With the LE, you get a cute little subcompact ragtop. It has a power topand enough interior room to fit two adults in comfort up front, two kids inback. That`s about it.

Not a lot of bells or whistles. Not a lot of power or performance, either. You want sun on your curls while motoring to the beach this summer?The LE fits the bill. You want rays on the loc 4-cylinder import from Brazil. A turbo boosted, 165-h.p. version of the engine is included in a $1,023 or$1,402 turbo package depending on how much glitz you add.

A 5-speed manual is standard, a 3-speed automatic is optional at $465.The EPA rating with the 5-speed is 27 m.p.g. city/36 m.p.g. highway. Withautomatic the rating is 22/29.

So add excellent mileage to the LE`s other attributes-open-air drivingand low price.

It`s a good package for the economy-minded provided you like hr locks;tinted glass; carpeting; reclining bucket seats; dual power mirrors; all-season, steel-belted radial tires; floor mats; and trunk lamp.

Air conditioning runs $720.