The Mercedes-Benz ML550 4MATIC was a variant of the W164 M-Class that debuted for the 2008 model year. The ML550 4MATIC was introduced when Mercedes fit the W164 ML500 4MATIC with their new M273.963 5.5L V8 engine. This change in engine lead Mercedes to change the ML500 4MATIC's name to ML550 4MATIC for the North American market, although for various foreign market, the ML500 4MATIC name continued to be used. The 5.5L V8 used in the ML550 4MATIC had an output of 388hp and 391 lb ft of torque that was sent to all four wheels via a 7 speed automatic transmission and Mercedes' 4MATIC all wheel drive system. Production of the W164 Mercedes-Benz ML550 4MATIC ended in 2011, when it was replaced by the next generation W166 Mercedes-Benz ML550 4MATIC.