This is exactly what it says on the tin. It is a V12-engined BMW Z3 roadster. Got your attention?

It was revealed on BMW M’s Facebook page, with a single line that reads: “We don’t know why a V12 engine was built into a BMW Z3 years ago. But it still looks impressive, doesn’t it?”

Well, yes, quite impressive indeed. Shoving large capacity engines into small cars is something Top Gear admires greatly. No word on when the one-off was built - nor what capacity that V12 is - but it certainly promises some fireworks.

The Z3 saw production from ‘96 to ‘02, and so using a little bit of guesswork, that V12 is probably the 5.4-litre twelve-pot from the 750i and 850i; a unit producing some 321bhp and 361lb ft of torque.

There’s no word on its performance, but the Z3 M - with a 321bhp 3.2-litre straight-six from the old M3 - did 0-62mph in around 5.4 seconds (the coupe ‘breadvan’ did it in around 5.1). Obviously, with so much more torque than this little sixer, the V12 promises interesting in-gear acceleration stats…

Of course, it’s not the first time M’s engineers have been let loose in the toy shop. In time gone by, they’ve knocked out an E34 M5 cabriolet, and ‘M8’ Coupe, and of course, an E92 M3 pickup.