While generating competitive performance numbers, the 2008 Pontiac Grand Prix pales next to its competitors when it comes to refinement and subtleties.
The Grand Prix’s base 3.8-liter V-6 generates 200 horsepower and 230 pound-feet of torque while delivering EPA numbers of 18/28 mpg. Designed in the 1960s by chopping off two cylinders from its 5.0-liter V-8, this tried-and-true powerplant gets the job done but is rather crude and gruff from a dynamic standpoint. Says Car and Driver, the Grand Prix “puts up impressive performance numbers despite a clear lack of refinement.” Criticizing the cast-iron V-6’s yesteryear technology, they call it “a bulldog among whippets” and gripe about its “asthmatic growl that’s probably intended to suggest sportiness.” ConsumerGuide finds the V-6 “provides ample power for everyday use,” while sister publication Consumer Reports labels it “responsive but rough and noisy.”
The optional engine, a significantly updated version of the very same small-block design responsible for the V-6’s blueprint, rings in at 5.3 liters, 303 horsepower, 323 pound-feet of torque, and it yields EPA numbers of 16/25 mpg. This engine is far smoother, more sonorous, and more refined. After all, a 90-degree bank angle was meant for a V-8, never a V-6. Still, Car and Driver feels that “putting 303 horsepower through the front wheels doesn’t make it a great car, just a quick one,” but admits that this engine yields “real performance.” Cars.com finds “it accelerates from a standstill with vigor, and the V-8 emits a much throatier, fuller exhaust note than the discontinued supercharged V-6.” Kelley Blue Book mentions the V-8’s Active Fuel Management (AFM) “helps deliver highway fuel economy figures better than some V6s.”
Both engines send their power to the ground through a torque converter and only four forward ratios. Says Autoblog, “the amount of usable power doesn’t make this car scream for a 5 or 6 speed automatic, but it sure wouldn’t be bad for fuel economy numbers.” Of the TAPShift feature, Cars.com notes it “work[s] well but may suffer a little delay.” With a selection of only four gears, it seems a questionably useful feature. ConsumerGuide declares the “Grand Prix's 4-speed is smooth and prompt.”
“Body roll was also conspicuous in transitions, accompanied by resolute understeer,” says Car and Driver. “The Grand Prix's suspension eases over most road flaws,” finds Cars.com, “but it gives the impression of avoiding rather than absorbing them.” Automobile feels, regarding the Grand Prix’s competent handling results, “g numbers and magnetic steering stand in for sensitivity to the finer points of chassis tuning,” and they add that its “chassis lacks suppleness, its steering lacks linearity, and its brakes lack bite.”