With the QX56, Infiniti has set its sights on the full-size luxury sport/utility market. Based upon Nissan's Pathfinder Armada, the new rear- and all-wheel-drive Q-ship retains most of the Armada's bodywork; everything is new forward of the A-pillar and the wheel-arch molding. Infiniti's waterfall grille, large Xenon headlamps, and family fascia help refine the somewhat quirky Nissan design.

The QX56 shares the Armada's 5.6-liter DOHC V-8 and five-speed automatic transmission, but an increase in compression to 10:1 boosts horsepower to 315 and torque to 390 pound-feet. Off-the-line acceleration is impressive. The electronic throttle is too sensitive at tip-in, but select AWD and a less-aggressive algorithm kicks in for easy modulation off-road.

Infiniti engineers revised the Armada's shock/spring rates and added a rear air-leveling suspension. On pockmarked roads, we found the ride compliant and well-controlled.

Noise, vibration, and harshness are further managed by triple door seals, thicker glass, and added soundproofing materials. Front- and second-row heated bucket seats are well-sculpted, and we like the best-in-class second-row legroom at 41.9 inches.

The plasticky Armada-like interior is our only real complaint. While there's good use of wood, aluminum, and leather trim, for a first-class cabin costing $50-large, we see too much polymer.

Geared to compete against the Navigator, Escalade, Range Rover, and Lexus GX 470, the QX56 is in esteemed company. But it has the stuff to nick a few sales from each.