Kuenheim was born in Juditten (Polish: Judyty) near Bartenstein, (East Prussia).

[3][5] Kuenheim fled the advancing Red Army in early 1945 and was evacuated via Pillau to Western Germany in March 1945 throughout the Operation Hannibal.

[3] He studied mechanical engineering until 1954 at the Technical University of Stuttgart[6] and joined the Quandt Group, BMW's largest shareholder since 1959, in 1965.

[7] Kuenheim "transformed BMW from a small, unfocused manufacturer of cars and motorcycles into a world performance luxury icon".

He is also an Honorary Senator of the Technical University of Munich, which named a building at the mechanical engineering faculty after him.