I need to see compareson between the M5 and 550I.

There is no comparison. The M5 is a racing beast. High performance for those that can afford an engineering master peace.

The 550I is based on the same chassis but the car is more comfort. Don't get me wrong you put the gas pedal down you will be launched forward.

Keep this in mind M = (Racing madness)

M5 hands down. It's the only car you need.