Mercedes-Benz redesigned its midsize sport-utility vehicle for 2006, giving it more power and larger dimensions, but with seating for five instead of seven. M-Class construction switched from truck-type body-on-frame to car-type unibody. Compared to the 1998-2005 version, the wheelbase grew by 4 inches, while the body measured 6 inches longer and 3 inches wider. Equipped with standard all-wheel drive, Mercedes' M-Class rivaled the Acura MDX, Cadillac SRX, and Lexus RX. The V6-engine ML350 and V8-powered ML500 versions returned. In the ML350, a 268-horsepower 3.5-liter V6 replaced a 232-hp 3.7-liter. The ML500's 5.0-liter V8 now produced 302 horsepower, versus 288 in the prior generation. A seven-speed automatic replaced a five-speed as the sole transmission. Both MLs had all-wheel drive without low-range gearing. Antilock four-wheel disc brakes and antiskid/traction control were standard. The ML350 had 17-inch wheels, while the ML500 rode on 18-inch rubber; 19-inchers were available for both. Front side airbags and head-protecting curtain side airbags were standard. Rear side airbags were available. MLs had a 60/40 split folding rear seat and a liftgate without separate-opening glass. For 2006, the shift lever moved from the center console to the steering column. Standard on ML500 and optional for ML350 was leather upholstery and wood/aluminum interior trim. Available for both were a navigation system, steering-linked xenon headlamps, and Mercedes' Tele-Aid assistance.