Four different Xterra models are offered: X, S and Pro-4X. All 2011 models are powered by a 261-horsepower 4.0L V6 engine, which is mated to either a 6-speed manual or 5-speed automatic transmission, though 2WD Xterra comes only with the automatic. The X and S models are offered in a choice of rear-wheel drive or a 4-wheel-drive system that has an electronically controlled part-time transfer case with low-range mode. The Xterra has serious truck underpinnings good for off-road adventuring, hauling heavy loads or towing up to 5,000 pounds. Its F-Alpha platform and fully-boxed frame are shared with Nissan's Titan and Frontier pickups, and the Armada and Pathfinder SUVs. In front, the suspension is an independent double-wishbone design with a stabilizer bar, while there's a heavy-duty solid-axle setup with leaf springs in back. Pro-4X models are supplemented with Bilstein gas shocks, which are comparable in on-road control but offer more wheel travel. With its many utility-oriented features, the Xterra is designed for active people who often carry heavy gear and need to go off-road. Side steps are built into the rear bumper for easy access to the roof rack, which has a latchable lid. The cargo area has an "Easy Clean" surface and ten cargo utility hooks, including six floor hooks capable of carrying up to 110 pounds each. In addition there's an available adjustable channel system in the cargo floor, similar to that offered in Nissan pickups, for securing bike racks or specialized gear. There's also space to secure and carry jugs of up to a gallon. Very short front and rear overhangs make the Xterra well proportioned for off-roading. It has several specialized features oriented toward rough terrain, including hill descent control and hill start assist, which both increase safety and help maintain control on steep slopes. Pro-4X models also include an electronic-locking rear differential. Safety features on all Xterra models include front-seat side-impact airbags, electronic stability control and anti-lock brakes. Roof-mounted side-curtain airbags, which cover all outboard occupants, are also standard. The base X model includes keyless entry and power windows, locks and mirrors, while the S adds alloy wheels, upgraded seats, step rails, a first-aid kit, a cargo net, roof-rack cross bars, a gear basket, the Easy Clean cargo surface and a C-Channel cargo floor. Stepping up to the Pro-4X model brings a host of solid off-road equipment, including Bilstein shocks, skid plates, off-road wheels and tires, fog lamps, roof-mounted lights, black body-side molding, a fold-flat passenger seat, blue cloth seat fabric and a leather-trimmed steering wheel.