IN 1982, Chevrolet restyled the Camaro, making it smaller. At the time, there was concern over fuel economy. The base engine in the compact (188 inches long with a 101-inch wheelbase) became the 2.5-liter 4-cylinder produced by Pontiac that got 20 miles to the gallon in the city but developed only 88 horsepower.

Today, the concern is performance, and Camaro is the only Chevy offered with a choice of a 4-cylinder, V-6 or V-8 engine. The ultimate Camaro is the IROC version of the Z-28. The Z-28 always looked good. With the addition of the IROC sports package, the car performs even better than it looks.

IROC is the acronym for the International Race of Champions. That`s the circuit in which a dozen Camaros are identically equipped for racing. The test is of the skills of the dozen different drivers that race them.

The IROC Camaro, with its port-tuned injection 5-liter V-8 engine, brings the flash and dash of the track to the street. The 0 to 60 m.p.h. time is about 7 seconds; the quarter mile takes 15 seconds–and that`s with automatic, the only transmission offered. The fuel economy rating is 16 m.p.g. city, 22 m.p.g highway, so you pay the price in mileage for leading the pack from the stoplight.

THE IROC Camaro is a Z-28 with more performance dress. The flared rocker panels extend an extra 3/4-inch closer to the ground, and IROC graphics on the doors warn others this is a special Camaro.

The IROC package includes 16-inch aluminum wheels, steel-belted p245/ 50VR-16 tires and halogen fog lamps. But the real beauty comes from the responsive port-injected V-8.

Chevy offers a choice of three engines for the IROC Camaro: a standard 5- liter carbureted V-8 with choice of 5-speed or automatic transmission; a high- output 5-liter V-8 with 5-speed only; and the tuned port injection 5- liter V-8 with automatic only that`s the best choice for performance.

GENERAL Motors Corp. has developed a series of multiport fuel-injected engines, the 3.8-liter V-6 from Buick, for example. Port injection differs from multiport in that it represents an additional step by tuning the air mix fed to the cylinders. Tuned port injection (TPI) differs from other GM injection systems (though it`s the same system as in the 5.7-liter V-8 in the `Vette) in that so-called “tuned“ runners or tubes run from the top of the engine to each port.

The tubes “tune“ the air like a pipe organ, based on their length and diameter. This tuning creates a pulse action for the air so that it moves in waves to each port. At the exact moment the intake valve opens, there is a ram effect on the air as it`s packed into the combustion chamber for more torque and horsepower and, therefore, optimum performance.

Computers do the work to provide the air-fuel mix at the proper moment and under a variety of operating conditions, from taking on the steep incline to sprinting even when the humidity i s high.

The TPI V-8 develops 215 horsepower, while 155 horsepower is developed in the Z-28`s base carbureted 5-liter V-8. You feel each of those horses galloping in the TPI powerplant. In case you`re oblivious to objects zipping out of sight, a rumble-tuned exhaust system gives you an audible reminder of the power.

A WORD of warning, however. Under no circumstances should you choose the Conteur Lear-Siegler seat. You may recall we pointed out that the Lear-Siegler seat in the Buick Century T-Type was uncomfortable. The seat in the IROC is worse. With all the dynamic vehicle looks and outstanding performance, you can`t enjoy it to the fullest because the seat`s side bolsters cut off ciculation and put your legs to sleep. Ironically, you pay $650 for the optional torture.

The IROC is available in black, blue, red, silver, yellow or white. The car we drove was black, really a class act, but we get to return cars when they need washing.

The IROC doesn`t come cheap. Base price of the Z-28 is $11,28 1, and you have to add $695 to that for the TPI engine, $659 for the IROC suspension- tires-wheels-graphics package and $425 for automatic transmission, so you`re up over $13,000 before you even start tinkering with sound systems or other options.