Nissan's 5.6-liter, 32-valve, double overhead-cam V8 offers impressive output, rated in the QX56 at 320 horsepower at 5200 rpm and 393 pound-feet of torque at 3400 rpm. When it was first released in 2004, the QX56 was at the top of the power chart in the large SUV class. Since then, Cadillac and Toyota have topped it, though it is still ahead of the Navigator. Towing demands high torque at low rpm and that's where the Infiniti's power is concentrated.
Acceleration performance is strong, but less than sparkling. The most likely reason for this is weight: An Infiniti QX56 AWD tips the scales at 5,903 pounds. That's slightly heavier than the Cadillac but a little lighter than the Lincoln. Nissan's overhead-cam engine sounds good, though, producing the appropriate big-V8 exhaust tones when you mash the gas. Not surprisingly, the QX56 is hard on gas. It is rated at only 12 mpg city and 17 mpg highway with all-wheel drive.
Braking is solid and linear, with good, manageable pedal feel. The QX56 features four-wheel disc brakes with ABS. The antilock brake system is barely felt when called upon and allows the driver to maintain steering control under hard braking. Electronic brakeforce distribution (EBD) improves stability under braking, while Brake Assist helps the driver get maximum braking performance in an emergency stopping situation. The electronic stability control system intervenes when the QX is pushed beyond the limits of grip, driving too quickly into a slushy corner, for example, and corrects the imbalance with little excitement.
Perhaps Q stands for quiet. Very little tire and road noise invades the cabin, thanks mostly to abundant sound-deadening material. Some wind noise is unavoidable, given the roof rack complete with cross rails, but it's reasonably muted.
The QX56's available all-wheel-drive system offers 2WD, 4HI and 4LO modes. A two-speed electronic transfer case allows the driver to select low ranges for 1st, 2nd and Reverse gears for seriously rugged terrain. The AWD system is designed to instantly distribute torque to all four wheels as road conditions warrant. Under normal driving conditions, the system operates in rear-wheel-drive mode for optimum fuel economy. But when conditions warrant, up to 50 percent of the power is transferred to the front wheels on demand, resulting in optimum traction. All AWD QX56s include heavy-duty skid plates for the oil pan, fuel tank and transfer case. Next Page