Fact: The IROC-Z and the Trans Am share the same basic GM F-car engineering.
Fact: Both the 350 IROC-Z and the Trans Am GTA utilize the same powertrains.
FICTION: Both cars are the same except for fascias, wheels and interiors.
Time spent in the cockpit will separate fact from fiction, because the difference between the Trans Am GTA and the 350 IROC-Z is like night and day. We had the opportunity to drive a 1987 Trans Am GTA for several days during a recent trip to Detroit, and we grew to like the GTA’s persona. Visually, the Trans Am GTA has all the appearance of an IMSA road racer, thanks to a very aerodynamic front fascia. In fact, race teams have had to do little revision to the Trans Am’s front end to make the race versions much more slippery through the air. The one drawback to the current design is it has negated an effective cold air induction system like the IROC’s, and consequently Pontiac had to rate the L98 at 210 horsepower as opposed to 220 for the IROC-Z.
Aside from the cold air induction, internally the Pontiac version of the L98 powertrain is the same as the Camaro. The 5.7 liter engine features a port injection set up with tuned runners and aluminum intake manifold. The only available transmission is a four-speed automatic, and the limited slip 3.27:1 rear axle is standard. GM saved both time and money in EPA-certifying just one drivetrain for both cars.
Where the GTA outshines the IROC-Z is in the corners. There’s really only one way to describe the Camaro’s suspension, and that’s tight. The IROC-Z fights you at the wheel and pounds you to the point of begging for a kidney belt. Pontiac took a different tact by lowering the spring deflection rates, using slightly firmer gas-filled shocks, ever so slightly more compliance in the bushings and a fat 36mm anti-sway bar up front and a 24mm bar in the rear. The thick Goodyear P245/50VR16 meats, mounted on a 16 x 8” “cross-laced” wheels, provide plenty of road adhesion and the GTA tracked the corners as squarely as a front heavy, rear wheel drive car can. This package, designated WS6, is standard on the GTA and available for the Trans Am and the Formula. We found high speed stability to be rock solid and secure, even during a 120 mph midnight jaunt up I-75, with just the deep-throated roar of the GTA’s exhaust to keep us company.
The interior had both positive and negative aspects. Our GTA was equipped with the available electronic gauge cluster, and it’s an option we could do without. The video game gauges are difficult to monitor; for two days we thought the fuel gauge was broken – we couldn’t read the dang thing! Fortunately, a complete analog gauge setup is standard on the GTA. The Delco UXI ETR AM/FM/Cassette unit had clean, clear sound with excellent low end response and we like the location of the rear speakers in the C pillars. The shifter is well positioned, with the knob contoured to fit the hand. The shift detent switch is side-mounted and thumb-activated. The IROC-Z uses a hardball-sized knob with a vaguely sprung detent button that was nearly impossible to shift manually. We thoroughly enjoyed using the shifter in the GTA, even if the gizmo tach was useless and we ended up shifting by ear. Even the shift lever is covered by leather. That’s class.
And then there are the seats. There isn’t a single American manufacturer who is offering forward seats as comfortable as Pontiac, and their new articulated bucket is as close to a Recaro as Detroit can come. Push a button in the left seat base and a pneumatic bladder in the seatback inflates, increasing lumbar support. Push another and the lower side bolsters inflate, cradling your lower back and providing indescribable support. The front of the seat cushion can be raised, lowered, or extended, eliminating “deadman’s leg,” that uncomfortable feeling when the circulation in your right leg is cut off because the seat cushion is improperly positioned, a common fault in most GM cars. The headrest has an infinite variety of positions. Anyone who complains they can’t find a comfortable seating position in the GTA must be built like Jobba the Hut.
We weren’t able to perform any time tests while we had the car, but performance is pretty much on a par with the IROC-Z. In situations where it really counts, that is out in the real world, the GTA was well-mannered. In Detroit rush hour traffic the GTA was docile, while on the freeways and back roads, the opportunity to drop the pedal was always fun, as the GTA was nimble and quick.
The fact is cost is also on a par with the 350 IROC-Z. Our GTA carried a sticker price of $19,113. Granted, it’s a lot of car, but it’s also a lot of money. Sales are down for both the F-cars, and that’s no wonder, since the Mustang GT provides the same amount of bang for much less money. Pontiac claims the GTA can click off 0-60’s in 6.4 seconds, however, we doubt few GTA owners will be taking their cars to the track. The GTA is meant for an open winding road, and the 5.7 liter engine and WS6 suspension are the perfect marriage of horsepower and geometry for spirited driving.
That’s the greatest attribute about Pontiac these days. Their cars have a certain panache, and they seem to have recaptured the maverick image of performance that they enjoyed in the sixties. Although they are affected by the GM “cookie cutter” school of styling, their products, from the Grand Am to the STE to the GTA, are unique and stand apart from the rest of the GM divisions. That’s been the main reason they are enjoying considerable success at a time when overall GM sales are falling fast and the corporation is suffering badly. And that, folks, is fact, not fiction.
Wheelbase:.......... 101 in.
Overall length:.......... 191.6 in.
Overall width:.......... 72.0 in.
Height:.......... 49.7 in.
Advertised weight:.......... 3435 lb
Passenger capacity:......... 4
Base price:.......... $13,259
Price as tested:.......... $19,113
Front:.......... MacPherson strur, coil spring, lower control arms, 36mm anti-sway bar
Rear:.......... Coil springs, live axle, torque rods, gas-filled shocks, 24mm anti-sway bar
Steering:.......... Recirculating ball, 12.7:1 ratio
Brakes:.......... Power assisted 10.5" vented disc, front and rear
Wheels:.......... 16" x 8" aluminum
Tires:.......... Goodyear Eagle P245/50VR16
Type:.......... V8, OHV
Bore and stroke:.......... 4.00 x 3.48"
Displacement:.......... 5.7 liters (350 c.i.)
Compression ratio:.......... 9.3:1
Advertised horsepower:.......... 210 @ 4000 RPM
Advertised torque:.......... 315 @ 3200 RPM
induction type:.......... Tuned-port fuel injection
Transmission:.......... Four-speed automatic
Gear ratios:.......... 4th: 0.70
Rear axle ratio:.......... 3.27:1