Now there's always an element of guesswork when analysing spy shots. Without any official information, you have to infer everything from bodywork alterations, where the car is in its lifecycle and, if there's some video, noise as well.

Hang on, this isn't a normal M4...

But with this

BMW M4

, we're stumped. For the large part it appears a roadgoing car, using the standard wheels, Michelin Pilot Super Sport tyres and even the steel brakes. But it won't take you long to spot where this car is drastically different from even an

M4 GTS

, leave alone a stock M4.

From the front there's a jutting chin spoiler, so prominent it needs to be tethered to the bumper. The tape on the bonnet doesn't appear to be too important, certainly not compared to the tarmac scraping side skirts. Not only do they make even those skirts on the Elise Cup 250 look a little apologetic, they even make the 19-inch wheels appear rather small.

That odd stance is no doubt helped by what's going on at the back. There's an incredibly aggressive diffuser just a few centimetres from the ground, combined with a gigantic rear wing as well. It's bigger than you'll find on a GTS but not quite DTM-esque, so could it perhaps be a test mule for the upcoming M4 GT4?

Whatever it is, we're intrigued by what the final result could be. Any further guesses, educated or otherwise, most certainly welcome!

