Equipped with a seven-speed automatic transmission and electronically managed 4MATIC all-wheel drive, the M-class is available in four models. The ML320 BlueTEC is powered by a 3.0-liter turbo-diesel V6 generating 210 horsepower. The ML350 is powered by Mercedes' latest-generation 3.5-liter gasoline V6, generating 268 horsepower. The ML550 uses an upgraded 5.5-liter, 382-hp V8 and the top of the line ML63 AMG uses a 6.3-liter, 503-hp V8. The extensively equipped M-Class includes standard features such as stability control and active front head restraints, as well as front, side, and side curtain airbags. For 2009, the M-Class has minor changes and the diesel engine changes from CDI to BlueTEC for improved emissions.