The BMW M57 is a straight-6 diesel engine produced from 1998 up to 2013 in BMW's upper Austrian engine plant in Steyr.
BMW M57
The BMW M51 is an inline-6 cylinder Diesel engine produced by the Upper Austrian BMW plant in Steyr from July 1991 through February 2000. Its predecessor is the BMW M21, the successor is the BMW M57.
BMW M51