While it’s not of the best quality, this photo shared by Mustang6G.com shows what appear to be four louver-style fender vents on a big-wing Mustang prototype. This is leading many to believe the car is a Mustang GT500 prototype equipped with a supercharged version of the GT350’s plat-plane-crank V8. And that engine needs to dissipate some heat.
These vents may have been present on a GT500 mule we saw earlier, but black cladding was covering them up. The photo was taken of a similar mule, or possibly the same one, in a garage or lab. You can see a few more shots of the prototype on Mustang6G’s forum, and we have spy video of a mule below. Previously spotted prototypes have been wearing Michelin Pilot Sport Cup tires, which are more aggressive than the GT350’s Pilot Super Sports. And then there’s that big wing out back. Mustang6G notes that this is not likely to be a refreshed GT350, since dealers have been told that car will not get any substantive updates when the face-lifted regular-strength Mustangs go on sale for 2018.