Super Chevy | Features

Sudden Impact

Is the production-bound Bonneville GXP the start of a performance renaissance at GM?

Courtesy of GMIllustrator

From an enthusiast's standpoint, the 1990s were a fruitless decade at GM. John G. Smale, and later Ron Zarrella, took decision-making power and creative input away from stylists and engineers, and instead decided to unleash an army of design researchers on the American public. This clipboard-shuffling strategy effectively let a mob design the products, and was extremely effective only in watering down the innovative ideas coming from GM's styling studios. These passionate designers would have much rather eaten clay than sign off on whatever ho-hum vehicle that got the go for production--and even when the corporate bureaucracy was at its worst, they always knew right from wrong. Those who had seen enough packed up and went, spewing ear-burning exit interviews about a time when GM was a different company.

But those who stayed got a reprieve in late 2001, when fellow enthusiast Bob Lutz was hired as chairman of GM North America. He immediately began to slice through the red tape, realign the right people in the powertrain and design departments, and hand the power back to its rightful owners. The only remaining question was: what would they do with it?

The word traveled fast at the 2002 SEMA show about the charcoal-colored row of GXP vehicles at the GM booth--but those conveying it weren't necessarily surprised. Many GM fans, including the staff of GMHTP, figured that the irrepressible Bob Lutz would have a few tricks up his sleeve for this event. And the GXP family was tricked-out: Vibe GXP, Grand Prix GXP, Sunfire GXP, Grand Am GXP, and Bonneville GXP seduced show goers from a corner of Pontiac's floor space. Their aggressive exteriors were devoid of cladding and topped with Shadow Black tri-coat paint. Interiors boasted custom leather seating surfaces and premium trim options. Suspensions were beefed up, aftermarket brake systems peeked through enormous wheels, and engines with up to 35 percent more horsepower over previous iterations lurked between fenders. Automotive scribes and everyday Joes alike loved the idea, but the subconscious has a way of reminding autophiles about GM's modus operandi--creating stunning concept vehicles, then treating them to a dusty storage garage somewhere in Michigan. But in a rapid-fire move in early November, trick turned to treat a mere week after SEMA had ended. The V8-powered Bonneville GXP had been tapped to provide thrill-seeking Pontiac buyers with a potent alternative to the hot new GTO, and it will be rushed into production for an early 2004 release.

The Bonneville GXP concept started as a promotional show car for GM. Full-sized attitude was the goal, and Pontiac responded by smoothing the Bonneville's lines and tuning up the front and rear fascias. Dark Argentinean Blue was the chosen color, accented by smoked headlights and taillights, Xenon fog lamps, and tinted glass. The body was dropped an inch and a half for a more aggressive look, and 5-spoke, 19-inch rims showcased mondo rubber and upgraded brakes. Although GM engineers wanted to drop a V8 into it immediately, the idea of installing a big mill into a turntable-bound Pontiac couldn't be justified. Instead, the Bonne's blown 3.8 was treated to a K&N filter, more boost, and a Corsa exhaust system, which pushed horsepower from the stock 240 ponies to 270. Not surprisingly, when Gary Cowger and Bob Lutz eyed the GXP they immediately fell in love with it. It was sent to the 2002 Chicago Auto Show, where it was applauded as a bold step forward for a division lacking the excitement that it advertised. After the superlative-filled Chicago venue GM knew it had something strong on its hands, and changes were made to prepare the Poncho for SEMA. But it stood to reason that distancing the upscale Bonne from the Grand Prix by offering a smoother V8 might make it stronger yet. And here's where this saga gets interesting: sometime between February and October, the GXP's supercharged 3.8/4T65E drivetrain lost out to a 4.4-liter, naturally-aspirated V8 connected to a stronger 4T80E transmission.

Most of the new motor's specifications are still hush-hush, but it has been said that the 32-valve, quad-cam mill (for the most part a carry-over from the Cadillac-based Olds Aurora V8) will more than likely share the Cadillac 4.6-liter Northstar's architecture and all-aluminum construction. In fact, the GXP's motor could very well be a de-stroked version of the L37 Northstar producing 285 horsepower. How much torque it will make is anybody's guess--we're willing to bet that GM won't have to push the 305 lb.-ft. torque capacity of the 4T80E transmission, but needs more than the 280 lb.-ft.-rated 4T65E can give.

Sources inside GM tell us that the 2004 Bonneville GXP is going to be very close to the SEMA iteration. The most obvious change at SEMA besides the V8 was the big and bold grille aperture, which had been accentuated for the show.

The grille will be less dramatic and more in-line with that of the Chicago concept, but the side panels and rear fascia should make it out of the factory intact. Initially it was reported that 10 exterior colors, including two premium tri-coats, would be available. However, GM hasn't decided whether or not it will limit the palette. Certain interior items will be changed, and vacuum-formed carbon fiber will be used. The production GXP will retain the lowered stance, but the 19-inch wheels on the concept will be replaced with more reasonably sized 18-inch units wearing rubber with a W speed rating. GXP's big rollers and V8 power will require structural modifications, although no specific changes to the chassis, save for bracing, have been released. A high-performance independent suspension claims compliant ride as well as good handling, but a lack of definite modifications prevents us from speculating. The aftermarket braking system won't see production; instead, a factory-built performance variant will have two tons of fun stopping this sedan.

If GM's 32-valve, quad-cam motor is indeed simply a de-stroked Northstar, it is hard to fathom why money would be spent to lower displacement 12 cubic inches before installing it in a performance car. Popular opinion would see this as a large waste of money when a few simple calibration changes could be made--GM may simply see it as a hierarchical decision. "You can't give a Camaro more engine than a 'Vette," one GM insider explained. "Regarding a 300-horsepower, flagship Cadillac and a Pontiac, it's the same thing."

However, the GXP will share the Caddy's stronger tranny. Unfortunately, this strength comes with a price: the 4T80E is nearly a hundred pounds heavier, at 292 pounds versus 195 for the 4T65E. It has been estimated that a 24 percent driveline loss exists with this trans, which is higher than the 4T65E's estimated 21 percent. The 80 does have slightly higher gear ratios down low--2.96 and 1.62 for First and Second, as compared to 2.92 and 1.56 for the 65. But when factoring in the driveline loss and extra weight, we suspect that the 285-horse, naturally aspirated GXP won't be any faster than the original concept's 270-horse 3.8. Consider the inferior weight transfer and other unpleasantness associated with a front-drive, V8-powered vehicle which will top 3,900 pounds, and we're looking at mid-14s in the 95 mph range on a good day. Not lightning-quick, but it will still beat the SSEi's mid-15s like a stray dog.

The Bonneville GXP is currently slated to replace the supercharged SSEi for the 2004 model year. Conversion to GXP status will likely take place through a combination of production line and post-production changes. No production run number has been set, but look for consistency with the current yearly SSEi sales.

With the GTO about to be crowned as Pontiac's flagship, the 2004 Bonneville GXP will be an upscale performance sedan that could carve its own upper-middle-class niche and entice buyers away from the Lincoln LS and Chrysler 300M--this is the kind of progress that softens retirement speeches. (Note the clock is ticking, however, as the V8 Hemi powered RWD 300N is scheduled to hit at approximately the same time.)

Hard-core enthusiasts will no doubt look upon this luxo-liner as a slower, porkier crown prince with a tiny bang/buck ratio (Remember the '96-99 V8 Taurus SHO?) and ask why the 275-horse Grand Am wasn't tapped for the first scheduled GXP treatment. And they would have a point, but keep two things in mind: GM has just taken a big step to get back into the performance business, and with the right people in charge, the good things sometimes trickle down.

2004 Pontiac Bonneville GXP
Layout: 4-Door, Front-Drive Sedan
Engine: 32-Valve, Quad-Cam V8
Displacement: 4.4 Liters
Power Rating: 285 hp
Estimated Torque Rating: 290 lb.-ft.
Transmission: 4T80E 4-Speed Auto
Wheels: 18-Inch Five-Spoke
Tires: 235/50/18, W-Rated To 168 mph
Estimated Curb Weight: 4,000 lbs.
Estimated Price: $38,000-$43,000
Estimated 1/4-Mile: 14.5@95 mph