2006 Pontiac Grand Prix Review

Specifications

New V8 Sports Fuel Saving Technology

During last months California International Auto Show in Anaheim, California, Pontiac unexpectedly announced at that it will produce a more powerful Grand Prix, the brands sporty midsize sedan entry.

For the past few generations top-of-the-line Grand Prix models have been equipped with forced induction via a supercharger, but for 2006 the top model wont be supercharged at all. Rather, following the newly introduced theme of Total Performance, the new GXP will feature V8 muscle, just like its bigger Bonneville GXP sibling.

With 30 percent of all Bonneville sales comprised of this top-line performance model, its only logical to think that Pontiac would want to duplicate the successful formula in its midsize sport sedan. While the Grand Prix GXP will feature V8 power, incidentally for the first time since 1987, the motor being used is of a completely different nature than that in the Bonneville GXP. Rather than the Cadillac Northstar derived 275 horsepower 4.6-liter unit with 32 -valves, dual-overhead cams and a resultant 300 lb-ft of torque, the Grand Prix GXP debuts General Motors all-new 5300 5.3-liter LS-4 V8 powerplant.

The new Grand Prix GXP will also offer distinctive styling, an upgraded interior, and enhanced handling dynamics. Starting with styling, the new model is sportier, more focused and seemingly intent on devouring miles of open road. Pontiac has given the GXP a revised front fascia with modified lower intakes. Only diehard Grand Prix fans will notice the chrome trim rings surrounding the twin kidney grille, but the front fender vents should be more obvious. Subtle rocker extensions give the GXP a purposeful stance, a look which thankfully replaces the boy-racer plastic cladding of previous models.

Like the Bonneville GXP, the Grand Prix GXP also features a revised tail end that includes an updated rear fascia complete with distinctive exhaust tips and a sporty deck-lid spoiler. Discreet GXP badging has been applied to the lower front doors, as well as the trunk lid. Final touches to this model include unique polished 18- inch five-spoke alloy wheels, wearing 225/50 WR 18 tires up front and 255/45 WR 18 rubber in back.

Inside, Pontiac hopes to lure in a few extra buyers with a more extravagantly equipped interior. The Grand Prix GXP features grippy Ultralux suede inserts on its perforated, leather-trimmed seats to hold the driver and passengers in place during aggressive handling maneuvers. Bright, brushed aluminum has been used as a trim accent, a welcome addition to the Grand Prixs “plasticky” interior. Other unique touches to the GXP model include a restyled instrument cluster and embroidered floor mats, both of which feature the GXP logo. Like most high-end Pontiacs, the Grand Prix GXP can be equipped with all the goodies and toys buyers have come to love including Head-Up-Display (HUD), climate control and a super-powerful sound system.

The heart and soul of the new Grand Prix GTP isnt in its styling or its amenities, but once again is under the hood. The new engine marks the first ever production application for a small-block overhead-valve V8 in a front-wheel drive configuration. Only Pontiacs own Bonneville GXP and the Cadillac DeVille currently offer V8 power and front-wheel drive, while the outgoing Cadillac Seville and Oldsmobile Aurora previously did. While the Grand Prix GXP wont necessarily be the most powerful front-wheel drive vehicle in the world when it goes into production, eclipsed by the DeVille, it will definitely leave behind most of its imported rivals, such as the Acura TL and Nissan Maxima.

Although its based off GMs latest fourth generation small block architecture, the 5.3-liter V8 has been redesigned for transverse (east-west) applications. Although the LS-4 is as long as an inline-four and as wide as a V6, several modifications including a shorter camshaft and a single-belt accessory drive system were required to fit the all-aluminum motor into the Grand Prixs engine bay. The pushrod-powered motor features high-flow cylinder heads similar to those used on the Corvettes LS2 V8, an electronic throttle and a new engine controller. In total, the motor produces 290 horsepower and 320 lb-ft of torque, 90 percent of which is available from 1,500 rpm to 5,200 rpm. It is capable of propelling the large, midsize GXP to 60 mph at just under six seconds.

Aside from packing a walloping punch, the new LS-4 motor also incorporates Displacement on Demand (DOD) technology, which made its first appearance on GMs midsize SUVs and pickups equipped with the 5.3 liter Vortec V8 engine earlier this year. By means of a sophisticated electronic controller, half of the motors cylinders are automatically deactivated when under minimal loads to reduce the amount of fuel needed for forward movement. In light-load situations, such as highway cruising, the engine acts as a V4 with alternating cylinders on opposite banks disabled. When the sensor detects a need for more power, the engine returns with all eight cylinders firing. GM claims that this technology improves fuel economy by 12 percent.

If you werent already aware, Chrysler introduced a similar technology in its hot new HEMI-powered 300C sedan. Honda is also offering cylinder-deactivation in its upgraded 3.5-liter V6, expected to power a variety of Honda and Acura products.

To cope with the additional power and torque from Pontiacs new V8, the domestic brand has employed a strengthened version of GMs trusty Hydra-Matic 4T65-E four-speed automatic gearbox. Although it shifts smoothly, and comes equipped with TapShift manu-matic functionality, the transmission seems a little outclassed in this day and age of 5- and 6-speed automatic gearboxes. Even General Motors offers 5- and 6-speed automatic transmissions on a variety of cars in price ranges both above and below the Grand Prix GXP, and lets not forget that DaimlerChrysler competes head on with the new GM model with its 5-speed automatic equipped Chrysler 300C, Dodge Magnum RT and soon enough, Dodge Charger sedan. Why General Motors doesnt spend a little more to improve performance and further reduce consumption is beyond me.

In order to make the most of the new powerplant, Pontiac revamped the suspension system of the Grand Prix for GXP use. The GXP employs high-performance Bilstein struts for improved damping, while springs with a higher rate cut back on lean and squat. Pontiac has also dropped the ride height by 0.4 inch, and has added a 0.7 inch diameter hollow rear stabilizer bar to further improve handling. Countering the forward thrust of the motor are a set of upgraded brakes, 12.7 inch cross-drilled discs up front and 12.0 inch units in the rear are standard, and are acted upon by high-performance twin-piston calipers. A state of the art four-channel ABS braking system by Bosch is standard.

While I dont doubt that the Grand Prix GXP will be able to negotiate corners, its highly doubtful that the V8/front-drive layout will be able to overcome the crippling effect of torque steer. Less powerful variants of the Grand Prix, including the Comp-G and GTP for instance, suffer from this ailment, so what makes GM think that more power will cure it? The GXPs 320 lb-ft of torque delivered through the front wheels will undoubtedly cause jitters and tremors through the steering column regardless of how wide and sticky the rubber is. But to be fair to Pontiac, it will take a test drive to be sure. Either way the Grand Prix GXP, like its Bonneville GXP sibling, should deliver a hair-raising drive.

As an expansion to both the Grand Prix and the GXP performance series, Pontiacs latest addition is little more than a predictable attempt at matching Chrysler in one-upmanship. Although it tops the horsepower count among front-drivers, it lacks the power and rear- and all-wheel drive benefits of the 300C. At least the LS-4 motor, with its advanced DOD cylinder displacement system, is a step forward for Pontiac.

The Grand Prix GXP is scheduled to start production during the first quarter of 2005, with pricing expected to be announced closer to its introduction date.