To this day BMW has never launched an M8 but the automaker did come close to doing so at one point, though the project was canned at the last minute. Back in 1990 BMW built a one-off prototype version of its then new 8-Series sports coupe and labeled it the M8.

The prototype featured a 6.0-liter variation of BMW’s S70 V-12 engine that developed 550 horsepower and it was clearly distinguished from the regular 8-Series on which it was based due to its missing headlights and subtle M8 badging. There was also a pair of side air vents located just in front of the rear wheels.

Car buffs may notice that the legendary McLaren F1 also featured an S70 series V-12 (albeit an uprated version), an engine that to this day enables the 21-year old supercar to remain the world’s fastest naturally aspirated production car thanks to a top speed capability of 240.1 mph.

McLaren F1

McLaren F1

It has now been revealed that the S70 V-12 engine was originally developed for the proposed BMW M8 supercar. Its design was essentially two S50B30 straight-six engines from the E36 M3, joined on a common crankshaft, and it was found to be instantly reliable during tests.

In addition to its application in the McLaren F1, the engine was also used in BMW’s Le Mans winning prototype race car in 1999. The story doesn’t end there, however, as a version of this engine was also tested in a first-generation X5 SUV complete with a manual gearbox and a 186 mph top speed.

And if that’s not enough, BMW even wanted to use the V-12 engine in a 25th anniversary M5 model but it couldn’t fit into the car’s engine bay. Instead, BMW released the one-off M5 CSL, which came with an enlarged version of the car’s 5.0-liter V-10.

Sadly, strict emissions and fuel economy regulations mean that we’re unlikely to ever see an S70 V-12 engine fitted to a production car again.