Following a mid-generation design refresh in 2009, the Mercedes-Benz M-Class midsize SUV remains essentially unchanged for 2009. The M-Class offers a roomy interior with upscale features like Burl Walnut trim and a premium leather four-spoke steering wheel, as well as such standard safety features as the Pre-Safe occupant-protection system, which automatically repositions the front seats and tightens seat belts to better protect the occupants if it detects an impending collision. In addition, the M-Class now comes standard with front-seat Neck-Pro head restraints, which help reduce whiplash in the event of an accident or sudden stop. For 2010, the M-Class consists of the ML350, ML550, and ML63 AMG trims, each with a different powerplant. The ML350 leads off with a 3.5-liter DOHC V6 engine, which produces 268 hp and 258 lb-ft of torque. The engine features continually variable timing on both the intake and exhaust valves, which helps conserve fuel while ensuring good acceleration off the mark and immediate throttle response at virtually any driving speed. The ML350 jumps out from 0-60 in 7.9 seconds, and manages fuel economy numbers of 16/21 mpg. Stepping up a notch, the ML550 comes equipped with a 5.5-liter V8 engine. It generates 382 hp and 391 lb-ft of torque, and drives the ML350 from 0-60 in 5.6 seconds. At the top of the line, the ML63 AMG retains its hefty 6.2-liter V8 engine, which pumps out 503 hp and an impressive 465 lb-ft of torque. With all that power and torque, the ML63 AMG roars from 0-60 in just 4.8 seconds. The ML550 posts fuel economy numbers of 13/18 mpg, while the ML63 AMG, with its big V8, manages only 11/15 mpg. The V6 and V8 engines in the ML350 and ML550 link to a seven-speed automatic transmission, which adapts its shifting patterns to the driver's style and features two overdrive gears to help conserve fuel at cruising speeds. The V8 in the ML63 AMG mates to a seven-speed AMG 7G-tronic automatic transmission with fingertip shift paddles located on the steering wheel, so drivers can manually shift gears when desired. In addition, the ML550 comes equipped with Mercedes' 4MATIC AWD system, which features a permanent 40/60 front-to-rear torque split. The system, which works in conjunction with a four-wheel electronic traction system, sends torque to the wheels with the most traction in slippery road conditions to ensure optimal grip and stability. An electronic stability program and antilock brakes with brake assist come standard on all M-Class trims. The M-Class can accommodate five passengers in its comfortable, well-equipped cabin. Standard features for the ML350 and ML550 include an 8-way power-adjustable driver's seat, a power sunroof, dual-zone climate control, and an 8-speaker audio system with speed-sensitive volume, a 6-CD changer, and an MP3 input jack. MB-Tex leatherette upholstery and Brown Birdseye Maple wood trim give the cabins an upscale feel. Leather seats and heated front seats remain options for both trims. As befitting its status as the top-of-the-line trim, the ML63 AMG ups the ante with a long list of upscale standard features, including Nappa leather upholstery, a 610-watt, 11-speaker Harman Kardon audio system with a 6-CD changer, a voice-activated navigation system with real-time traffic information, and Mercedes' COMAND system, which drivers can use to manage the audio, climate control, and navigation systems. In addition, the ML63 AMG includes a number of unique features designed by AMG, Mercedes' in-house sport tuner, including AMG front sport seats, an AMG-designed ergonomic sport steering wheel, brushed stainless steel sport pedals with black rubber pads, and an AMG instrument cluster. Exterior features for the M-Class include a distinctive front grille, chiseled bumpers, running boards, front foglights, heated power mirrors, taillights with smoked glass, and chrome exhaust tips. The ML350 and ML550 ride on 19-inch alloy wheels with all-season tires, while the ML63 AMG cruises on 20-inch AMG-designed alloy wheels with high-performance tires.