I see they got creative with the rear end for aerodynamics. None of the road cars have that ducktail and it's a pretty massive style and aerodynamic deviation from the road car. I'd expect that they release a high-performance version with that ducktail to comply with the rules. Note that the 911 GT3 does have the same ducktail spoiler as the GT3 R, although it's nowhere near to the degree as this Benz where they've just completely redesigned the rear end altogether.
It illustrates that the road car has terrible downforce characteristics by nature which is why it's got the pop-up spoiler, a feature that - correct me if I'm wrong - only the McLaren road car has in the category. Various 911s do but the GT3 and GT2 do not.