"Source Edmunds Inside Line" The 2009 Pontiac G8 GXP was the most powerful muscle car in Pontiac history. Also formerly known as the Performance division of General motors.
The Most Powerful Production Pontiac...Ever? Ace No. 1 is the 2009 Pontiac GXP's LS3 V8, the base engine found under the hood of the 2008 Corvette. Displacing 6.2 liters (376 cubic inches), the G8 GXP version makes 415 horsepower and 415 pound-feet of torque, some 54 hp and 30 lb-ft more than the G8 GT's V8 engine.
The 2009 Pontiac G8 GXP is the most powerful production Pontiac built to date. Really.
You could argue that the 1970 Pontiac Trans Am could be equipped with a 400-cubic-inch Ram Air V, which was rated at 500 hp. But this special-order engine was a dealer-installed item, and it would never withstand a grocery run on 91 octane gasoline or live long enough to meet a 100,000-mile powertrain warranty, and hooking one up for a 2008 smog test would be, um, futile.
Moreover, the 2009 Pontiac G8 GXP's 415-hp rating is certified as an SAE net output, which means it was produced under tightly controlled test procedures that include the presence of an independent observer.
Twisting the key brings this engine to life with a burbling idle that the 6.0-liter V8 of our 2008 Pontiac G8 GT long-term test car can't match. There's plenty of life under the throttle pedal, as the GXP responds with the kind of healthy shove to the backside you'd get if someone put a sign on the back of your jacket that said, "Kick me."
The exhaust note that comes from the GXP's low-restriction exhaust system contains just enough of that high-school rock-and-roll soundtrack to make us want to stand on the power pedal whenever possible, yet it's not offensive enough that the old guy down the street will shake his cane at us. And did we mention the off-throttle burble?
But there is a dark side. The GXP's fuel consumption figures are expected to settle near those of the ZR1 Corvette, which are 14 mpg city and 20 mpg highway. Plus the ZR1 gets slapped with a $1,700 gas-guzzler tax, so it's likely the GXP will, too.
Shift Change When it comes time to grab the next gear, we actually can. Ace No. 2 in Pontiac's program for the GXP is the same Tremec TR6060 six-speed manual transmission we experienced in the Holden Commodore SS. Except here the shift lever is under our right hand, where it belongs.
There is one little catch, however. In a reversal of usual practice, the same Hydra-matic six-speed automatic found in our G8 GT is the GXP's standard offering. You have to fork over $695 extra to get the six-speed manual.
At least it's a good one. The lever action is sure and the gates are well-defined. And having full command of the transmission makes the LS3 much more of a willing partner, especially when corners are thrown into the mix.
We're not as convinced about the clutch, however. The engagement point is easy enough to detect, but the pedal effort is too light. The Luk single-disc clutch and single-mass flywheel are the same found in the bell housing of the 361-hp Holden Commodore SS, but we're assured there's more than enough capacity to deal with the LS3.
The same limited-slip rear end found in the G8 GT and Commodore SS is fitted to the GXP, but with a couple of important changes. The GXP's final-drive ratio is shorter, as the Holden's 3.45:1 rear end is changed to 3.70 here when the manual transmission is in place. The automatic variant enjoys a 3.27 rear end instead of the G8 GT's 2.92 gears. And the GXP's ring-and-pinion gears are shot-peened and phosphate-coated for enhanced wear and durability, something that can't be said of the rear ends of some other high-output cars.
Rubber Meets the Track Our instrumented acceleration test runs peg the performance of the 2009 Pontiac G8 GXP with its six-speed manual transmission at 5.2 seconds to 60 mph (4.9 with 1 foot of rollout like on a drag strip) and 13.4 seconds at 105.9 mph in the quarter-mile. That's about 0.4 to 0.6 second quicker than the G8 GT and Commodore SS. Pontiac points out that the automatic-equipped GXP will do 0.2 second quicker still.
The most obvious change to the chassis is the fitment of larger 14-inch ventilated brake rotors with Brembo four-piston fixed calipers in front. Bigger brakes mean the 19-inch tires are now standard, and they're the same 245/40R19 Bridgestone Potenza RE050A summer performance tires that are optional for the GT. Here they're mounted on unique forged-aluminum wheels that weigh about 1 pound less apiece than the GT's optional wheels.
The GXP's stopping distance from 60 mph comes in at 110 feet — the same result as the G8 GT with the same tires, but smaller brakes. The benefit from the new brake package expresses itself as increased fade resistance after numerous hard stops, and excellent pedal feel.
The GXP carries the so-called FE3 suspension package with sport-tuned struts and shocks that feature firmer damping rates, which replaces the FE2 setup found in the GT. No further changes apply to the front suspension, but the rear gets a 2mm-larger stabilizer bar (from 18mm to 20), a lower control arm with an outer ball joint instead of a rubber bushing, and a revised toe link.
There are no specific steering system changes, but these mods alone give the GXP better turn-in response and precision along with a reduced tendency toward understeer. The car's ride quality doesn't suffer much at all from the extra damping control, either. In fact, we like the way the GXP deals with uneven asphalt better than the sometimes soggy feel of our G8 GT.
None of this adds up to a measurable benefit at our test track, presumably because our G8 GT features identical tires. The GXP's 0.84g effort on the skid pad is on par with our GT, but its slalom time of 63.6 mph is actually slightly slower. Our test pilot theorizes that the GXP's stiffer rear stabilizer bar that helps reduce understeer in corners might be making this 4,010-pound sedan a little pendulous through the slalom as the tires heat up after four or five consecutive cones with the stability control shut off.
Visually Similar Perhaps the most unexpected aspect of the 2009 Pontiac G8 GXP is its visual similarity to the G8 GT. Apart from the wheel differences between the two cars, the GXP's handsome front and rear fascias aren't distinctive enough to get your attention unless you park a GT alongside. And you have to brandish a ruler to confirm that the quad exhaust tips are, in fact, a half-inch bigger.
But perhaps that's the point after decades of Pontiac scoop-and-cladding excess. Still, we think the ready-made stand-up wing from the 2007 Holden Commodore SS is just the thing for this car if you can get one, as the GXP's spoiler seems a flaccid carry-over from the GT.
Inside the cabin, you'll find that the optional leather-upholstered seats are now standard, but with large GXP logos embroidered into them. A heavily sculpted steering wheel from the Holden Commodore SS-V makes its first appearance. We'd rather it didn't, because its cartoonish contours don't fit our hands. Everything else inside is pure GT fare, including new-for-2009 Bluetooth connectivity.
Now How Much Would You Pay? The 2009 Pontiac G8 GXP is expected to start at just over $39,000, including destination and the compulsory gas-guzzler tax. Our test car has the two most significant options, the six-speed manual and a $900 sunroof. We figure the as-tested price of our particular GXP settles just below the $41,000 mark.
If this holds true, the 2009 Pontiac G8 GXP will be cheaper than the similarly optioned SRT8 versions of the Chrysler 300 and Dodge Charger. And you can't opt for a manual in either one of those cars at any price.
Pontiac has been building up to the GXP for a long time and this time it's got some serious wide-track excitement to sell. You could argue that the 2009 Pontiac G8 GXP is more like a four-door Trans Am than a regular G8.
But the question is, has Pontiac held onto its best cards too long? Can the GXP show everyone that the G8 is good enough to make Pontiac a brand to be proud of?