Originally Posted by IFlyX5

It's the same engine, but tuned a little bit differently for the 550i, 650i, 750i, and 4.8is. The same engine in the 4.8is gives you 369 lb-ft instead of just 360 lb-ft in the rest. Horsepower is 360hp across the board, except in the 4.8is where it is only 355hp.