AMG was originally founded in 1967 as a manufacturer of racing engines. Originally, the company was an independent engineering firm, but in 1990, DaimlerChrysler took a controlling interest, followed by a full takeover in 2005.
Initially AMG started with designing and testing racing engines, and later on it moved to building custom road cars based upon standard Mercedes cars, which remains its main focus today.
AMG models are defined by a more aggressive exterior look, more powerful engines and upgraded performance figures. The current models are generally offered with a 5.5 liter, V-8 twin-turbo engine - the models wearing a "63" in their nomenclature and a 6.0 liter, V-12 BiTurbo engine in the model with "65" in their names. Most recently, however, AMG has added a 2.0-liter, inline-four cylinder engine to its arsenal for compact Mercedes models, and they typically don the "45" nomenclature.
Check out the video to learn a few more things on the AMG history,