But what may not be so obvious is that there's a big asterisk to the formula when you start applying it to a front-wheel-drive car. The footnote reads something like this: "Put enough power through a front-drive system, and the driver will find himself turning right or left when he was planning on straight ahead.
It's called torque steer, and it's the major limiting factor in front-drive performance cars. Despite various engineering advances, the problem persists in cars such as Acura's otherwise superb TL, which sends horsepower through a six-speed manual transmission to the front wheels via a helical limited-slip differential.
But in the Grand Prix GXP, with more horsepower at rpm and a lot more torque pound-feet at rpm , torque steer is not a serious issue. There are hints-a little tugging when the driver cracks the throttle at low speed-but no real wrestling. How'd they do that? By adopting a measure no one else has ever put into production. More in a minute. But first, another front-engine, front-drive problem, one that's even more chronic than torque steer.
As a consequence, the front wheels carry more than their fair share of the car's mass, diluting the ability of the tires to transmit steering inputs. Worse, the front tires are also required to transmit power to the pavement, and all things being equal, the poor things just can't handle their multiple assignments as well as the front tires of rear-drive cars.
The result is understeer. The faster the driver herds the car into a turn, the more it wants to go straight. Highs: Mellow V-8 rumble, plentiful V-8 torque, excellent road manners. Pontiac's solution to these two inherent front-drive directional control problems-understeer and torque steer-is unique. So we put our computer guys on it, and they came back with a recommendation for a smaller rear tire, to give the car better balance. This is a radical departure from conventional wisdom, and the idea proved out in initial testing.
But there was a nasty side effect: Increasing the contact patch at the front amplified torque steer. However, after experimenting with a number of different tires from a variety of manufacturers, Minch and company decided the problem lay in the tire's construction-the way the plies were wrapped-and not the footprint.
With sufficient application of power, the tire sidewalls distort, thus affecting directional stability. Bridgestone, the supplier of choice, was initially reluctant to accept this theory, but when the GXP team achieved improved results using an off-the-shelf tire from another maker, the Bridgestone people got to work and developed a tire that delivered the desired performance.
Other elements of the GXP package include Bilstein monotube front struts--a first for a front-drive GM car, according to Minch--and forged aluminum inch wheels 8. Still another challenge was fitting the 5.
Although GM has flirted with this idea in the past—our man Csere drove a Chevy Lumina mule with V-8 power more than 10 years ago—it wasn't as easy as simply greasing the thing up and cramming it in there.
The powertrain troops had to develop a tidier version of the 5. The net of the redesign was a reduction in overall length of "about an inch," according to Minch, which was enough. Lows: Hints of torque steer, hefty curb weight, high steering effort at low speed.
The transplant also required mods to the 4TE four-speed automatic to handle the extra torque and a three-point engine-mount system designed to damp the V-8's torque rotation at full throttle. Pared down, the 5. The all-aluminum V-8 is actually lighter than the supercharged iron-block 3. But how does it stack up in terms of Pontiac's BMW objective? Let's be clear. This ain't a BMW. It's not as agile as the sports-sedan pacesetters from Bavaria, and even though the unique tire stagger puts the GXP's responses much closer to neutral, the Pontiac's defining trait is still mild understeer.
The four-speed TAPshift manumatic is better than some we've experienced, leaving upshift decisions totally in the hands of the driver, but the transmission offers only four speeds to play with.
The engine's torque band is so broad, and the transmission's up- and downshifting so prompt in full automatic mode, that the driver can achieve pretty much the same levels of haste by simply putting the lever in D and leaving it there.
That said, the GXP is not without some appealing traits. If it's not quite BMW eager in transient response, it's not too far off the curve, and if the GM Magnasteer II system is artificially heavy at low speeds, it's quick 2. The GXP turned in a ho-hum 0. And braking performance— feet from 70 mph, and zero fade—is on par for this class. The net is a forgiving and capable four-door, arguably the most entertaining sedan Pontiac has ever offered.
There are some interior elements that enhance the entertainment. I wanna keep the car but i was wanting to put a new engine in it so i can keep it for longer but i was hoping to u Review another car. Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus.
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