C/D Upfront - 2005 LS4 Pontiac Grand Prix GXP - ATTN GTP Crew Eight pretty good reasons to consider the Grand Prix - Pontiac's growing line of energized sedans to get a new member BY TONY QUIROGA January 2005 GXP is Pontiac's growing line of energized sedans, and now it's going to get a new member. Joining last year's V-8-powered Bonneville GXP will be the Grand Prix GXP this spring. It replaces the Grand Prix GTP Comp G. Like the Bonneville GXP, the GXP version of the Grand Prix will get a V-8 engine, although it's not the DOHC Northstar unit from the Bonneville. Instead, the Grand Prix gets a transversely mounted pushrod all-aluminum 5.3-liter V-8 that is a smaller version of the 6.0-liter LS2 mill from the Corvette. Pontiac claims the small-block V-8 is lighter than the iron-block supercharged 3.8-liter anvil that did duty in the Grand Prix Comp G, so expect the GXP to weigh less than the Comp G. Cylinder deactivation will purportedly boost fuel economy by up to 12 percent by running on four cylinders in cruising and coasting situations. With an estimated 290 horsepower and 325 pound-feet running through the front tires, the sprint to 60 mph is expected to take about six seconds. A rather unsporting four-speed automatic that includes Pontiac's TAPshift manumatic setup will allow the driver to select the proper gear when cornering; to improve handling, the front tires will be larger than the rears. That's right, the fronts will be 255/45R-18s on eight-inch-wide forged aluminum wheels, and the rears will be smaller 225/50R-18s riding on seven-inch-wide wheels. Both ends benefit from Bridgestone's grippy RE050A tires. By using larger tires up front, GM hopes to decrease understeer and create a balanced chassis. A lowered and stiffened suspension will also be on the bill to keep the GXP locked to the earth. Interior modifications include a new instrument cluster, suede seat inserts, and GXP badges in case the V-8 rumble isn't enough to remind you of the grander nature of your Prix. The GXP Prix's price had not been announced, but we expect it will cost a bit more than the Comp G's $28,615.