In February 1987 finally officially announced that it was putting the first 12-cylinder engine in a German saloon in about 50 years. The BMW 750i made its official debut a month after that at the Geneva Motor Show.
The V12 was developed from scratch and produced 300 horsepower from its naturally aspirated five liters. The M70 was designed using two M20 straight-sixx engine blocks mounted at 60 degrees from each other. The bore and stroke was the same, but they installed two Motronic ECUs, one for each side, so the motor could run on half the cylinders if something happened to the electronics.
The same 300 hp hp motor was fitted to the E31 850i starting in 1989.
“Its refinement, low noise levels and excellent balance between performance and fuel consumption set new benchmarks in engine design. These objectives were achieved by using state-of-the-art technologies and a raft of innovative ideas right across the board. In short, the BMW 750i’s 12-cylinder engine had been built with the aim of setting a new and groundbreaking benchmark that would occupy the highest echelons of automotive engineering,” BMW says.