THIS IS A TALE of two cars -- the red 1988 Buick Regal Limited Coupe and a blue model of the same name and make.

Both were assembled at General Motors' Autoplex plant in Oshawa, Ontario. Both had low mileage at time of delivery, under 3,000 miles.

I wound up driving two Regals because of an unexpected change in the test car schedule.

Funny, how things work out.

The red Regal was stunning -- great body, great performance. The blue Regal was a cosmetic and performance nightmare.

How can this be?

The 1988 Regal is part of the GM-10 program, a laudable effort by America's largest automaker to scrap look-alike cars and attain world-class quality in the process.

The program mostly seems to be working. Though sharing many identical components, the GM-10 cars, including the Pontiac Grand Prix and Oldsmobile Cutlass Supreme, do look different. And the cars are considerably better than their predecessors in overall quality and design.

But GM seems afraid of success. The company acts like a high schooler who flunks to avoid rising too far above the crowd -- getting "As" and "Fs" in the same subject under the same teacher

'Tis goofy behavior -- perhaps forgivable in an adolescent, but unpardonable in a company seeking thousands of consumer dollars for its individual products.

C'mon GM. It's time to grow up.

Complaint: Auto manufacturers and dealers produce and sell some lemons. We all make mistakes. Intellectually, I can accept that. Emotionally, it would be hard to live with after spending more than $15,000 for a "perfect" car.

The blue Regal coupe's misaligned mouldings and seams in the rear cabin, its wayward alignment where the right-side interior door panel is supposed to meet the curvature of the dashboard and its erratic (surge and hesitate) engine performance were simply unacceptable.

Praise: Kudos to the red Regal coupe, which differed from the blue car in minor details -- a "sports" steering wheel versus a "traditional" steering wheel with fake wood-grain inlay, for example.

Fit and finish on the red Regal were excellent, world class. The car was a pleasure to sit in.

Head-turning quotient: Resembles Ford's Taurus/Sable cars, but the 1988 Regal is distinctive and attractive.

Ride, acceleration and handling: Excellent ride and handling in both the red and the blue. Excellent acceleration in the red.

GM's usually up-to-snuff, 2.8-liter, multiport-fuel-injected V-6 is standard in the 1988 Regal. The engine cranks out 125 hp at 4,500 rpm. Unfortunately, in the blue Regal, the engine was just cranky.

Changes: The Regal has been changed from rear-wheel-drive to front-wheel-drive for 1988; and the car is 8.4 inches shorter in overall length, down to 192.2 inches from 200.6 inches in the 1987 model. Also, the new Regal is designed for easier repair and maintenance -- most major underhood components are easily accessible.

Sound system: AM/FM stereo radio and cassette, with electronic seek and scan, by GM/Delco. Excellent in the red and the blue.

Mileage: About 26 mpg in the red, versus 24 in the blue (16.6-gallon tanks, estimated range of 430 in the red and 396 in the blue on usable volume), combined city-highway, mostly driver-only, driving in the District of Columbia, Maryland and Virginia.

Price: For the red Regal, $15,411, including $2,199 in options and $439 destination charge. For the blue, $14,997, including $1,785 in options and $430 destination charge. Base price on both is $12,782, and dealer's invoice price on both cars (without options) is $10,617.49.

Warren Brown covers the auto industry for The Washington Post.