BMW M4 GTS Spied?

BMW's M4 is still box-fresh, but that hasn't stopped BMW from thinking about the next step forward for its high-performance sports car.

Spied recently while testing in Europe, this prototype (and it definitely is a prototype, ignore the Moto GP Safety Car decals) sports a jutting lower lip spoiler, a huge rear wing, carbon-ceramic brakes and bigger rubber.

A roll cage and racing bucket seats can also be spied through the glass. 

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