fritz:
a) The prototype road car already has a ram-effect air vent at the leading edge of the engine cover for combustion air and engine bay cooling. 

b) The Turbo's side vents would be way over-sized just for combustion air, unless they were just meant to be a gimmick, "more for show than go". 

There is a third possibility: Maybe Weissach had some rear fenders left from a 991 Turbo/S crash test/test mule and they didn't want to put them to waste, so they used them for the GT3 RS mule until they actually start manufacturing the larger sized rear fenders without the air inlets or smaller air inlets? 

A couple of years ago, shortly after the 997 Turbo presentation, I visited Werk 1 and noticed a couple of 997 Turbo mules (partially with camouflage) there in the backyard, mules which were ripped off of their parts, some were even half "done"...

So maybe... Smiley


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RC (Germany) - Rennteam Editor Porsche 991 Turbo S (Sept. 2013), Cayenne GTS (958), BMW X3 35d (2013)