For a few days, it was a genuine automotive enigma. Here was a Pontiac Grand Prix, clearly badged as a GXP, yet shrouded in mystery. No Monroney label, no detailed information in the provided sales brochures, and even a quick online search yielded little to no immediate enlightenment. It was, however, undeniably a Grand Prix, but something was different. Subtle GXP badges adorned its sides, and more intriguingly, a discreet V-8 emblem graced the rear. This was no ordinary Pontiac Grand Prix.
Even before the engine roared to life – a deep rumble unmistakably emanating from a GM small-block V-8 – visual cues hinted at Pontiac’s high-performance intentions. The Grand Prix GXP boasted subtle yet distinct styling changes compared to its standard counterparts. Aggressively sculpted front and rear fascias, along with extended rocker panels, gave it a more planted and muscular stance. Polished 18-inch aluminum wheels were another clear indicator, showcasing speed-rated Bridgestone Potenza tires, and hinting at the performance lurking beneath. Vented, cross-drilled brake rotors and red-painted calipers peeked out from behind the wheel spokes, further solidifying its sporting credentials. Even the ride height appeared to be subtly lowered, adding to the car’s purposeful demeanor.
Gradually, the pieces of the puzzle began to fall into place. A faxed price sheet from GM and more in-depth online research finally revealed the story: Building on the momentum of the Bonneville GXP launched the previous year, Pontiac had indeed shoehorned a V-8 engine into the Grand Prix engine bay – the first time since 1987 – to create an even more potent, high-performance variant: the Pontiac Gp Gxp. What I was driving was an early production model of this exciting new machine. However, instead of the Northstar-derived DOHC 4.6-liter V-8 found in the Bonneville GXP, the Grand Prix GXP was equipped with a 5.3L OHV V-8, complete with Displacement on Demand (DOD) technology, also known as Active Fuel Management.
But deciphering the “what” of the GXP didn’t immediately illuminate the “why.” GM’s performance portfolio was already well-stocked with performance-oriented four-door sedans. The existing Grand Prix GTP, with its supercharged 3.8L V-6 producing 260 horsepower, was hardly a slouch in the performance department. The rationale, however, was clarified by Dave Muscaro, GM’s assistant chief engineer of small-block V-8s for passenger cars: “There is nothing like the satisfying feel of a V-8 engine, and the 5300 V-8 provides a level of performance rarely available in competitors’ vehicles.”
In the Pontiac GP GXP’s case, this 5.3L V-8 translated to a robust 303 horsepower and over 325 pound-feet of torque. In real-world terms, this meant a zero-to-60-miles-per-hour sprint in approximately six seconds, according to GM – impressive for a car weighing around 3,630 pounds (1,650 kilograms). The torch of performance for the Grand Prix lineup was thus passed from the $34,160 GTP to the more potent $37,110 GXP.
But the GXP designation signified more than just a boost in horsepower, explained Jim Bunnell, then Pontiac-GMC general manager. “It’s an extension of Pontiac’s total performance lineup. We’ve taken a systematic approach to elevating all aspects of the Grand Prix’s dynamics, ratcheting up everything from handling to styling and refinement, to give performance-oriented customers the exhilarating driving experience they desire.”
Setting aside any debates about GM’s continued reliance on overhead valve engines, the GXP’s all-aluminum V-8 was undeniably a strong point. GM touted it as the third displacement variant of the Gen IV small-block, which also saw duty in vehicles like the Chevy SSR, GTO, and Corvette, as well as various SUVs. For the Grand Prix GXP application, the engine was modified to accommodate the transverse, or “east-west,” mounting configuration required by the front-wheel-drive chassis. This necessitated alterations to the engine’s overall length, including a shorter crankshaft and a single-belt accessory drive system.
In the GXP, the engine delivered potent acceleration from a standstill, swiftly reaching and maintaining desired speeds. It was also a relaxed cruiser, where the Displacement on Demand (DOD) system was intended to provide up to a 12-percent improvement in fuel economy by seamlessly deactivating half of the engine’s cylinders under light load conditions.
However, a significant portion of the V-8’s inherent fun factor was somewhat diminished by the four-speed automatic transmission, equipped with TapShift manual shift control. Simply put, the transmission felt like it was in dire need of an additional gear, or perhaps two. Whether it was the transmission’s limitations or the influence of the DOD system, a considerable prod of the accelerator pedal was often required to awaken the GXP from its relaxed cruising state for any meaningful part-throttle acceleration. Once you did commit and press the pedal firmly, however, the Grand Prix GXP responded with a surge of V-8 power and rapid acceleration.
The handling dynamics of the Pontiac GP GXP presented a mixed bag as well. The positive aspect was undoubtedly the upgraded braking system. With substantial 12.7-inch diameter discs up front and 12-inch discs at the rear, complemented by ABS, the Grand Prix GXP’s stopping performance was undeniably top-notch. The ride quality, however, was less impressive. Typically, a sedan with a long wheelbase, such as the Grand Prix’s 110.5-inch (2,807-mm) wheelbase, tends to smooth out imperfections in the road surface. However, the GXP was fitted with a revised sport-tuned suspension, incorporating higher-rate springs and Bilstein gas-charged struts for enhanced damping control. While this resulted in reduced body roll during cornering – aided by a rear stabilizer bar – the ride quality suffered noticeably. Even minor bumps and potholes were transmitted rather sharply into the cabin.
Ultimately, the Pontiac GP GXP emerged as an intriguing but imperfect performance sedan that seemed to require further refinement. While it executed many aspects adequately, it lacked a standout quality that truly elevated it above the competition. Yet, there was a desire to see Pontiac persist in this direction. American-made, generously sized four-door sedans with genuine sporting credentials were becoming increasingly scarce. The Chrysler 300C couldn’t be the only option in this niche market. The Pontiac GP GXP, despite its flaws, represented a commendable effort to inject some much-needed muscle and excitement into the full-size sedan segment.
Original Review Source: http://www.canada.com/montreal/mont…montrealgazette/news/driving/story.html?id=8d49ce89-8ba1-48a5-878f-65076d27e0ae
