One of the most fascinating things about the performance arm of a big car company is their 'skunk works', where they keep the top-secret development mules we're not supposed to know about and - and previous prototypes that never made it into production.
BMW's M division has more than its fair share of 'cars that never were', such as the M3 bakkie and the M8, but, even by M Division standards, this one was a wild and very well-kept secret until somebody at M posted these pictures on Facebook recently.
As near as we can tell, it's an early-nineties Z3 with a 5.4-litre M73 V12 engine which, when used in the 7 Series of the time, was good for 243kW at 5000rpm and 490Nm at 3900.
And even in that relatively mild state of tune, that would have been enough to make the Z3 very skittish indeed and - given the weight of the engine - probably prone to dramatic understeer like an American muscle-car.
Not the image that the bean-counters in Blue Propeller World like to project, which is probably why it never got the green light for production, but it's nice to know that the whitecoats in Munich don't take themselves seriously all the time.