This car is the Shelby GT350 which has been seen at the Nurburgring while it is testing. There are some details, that can be made out in the spy pictures, which show that it really is a GT350, rather than some other type of Ford Mustang. The test mules for the GT500 have been bulked up and muscly like the original vehicle, but this test vehicle looks rather lighter which is more like the GT350 that we already know.
The GT350 is taking over form the Mustang Boss 302 which was a vehicle that was just around for two years but was a very balanced track car. The new car will have the same V8, 5.8 litre supercharged engine and manage to be the most beast like of the Mustang range. However, it will manage to do all of the fine handling and track ready features without forced induction.
The new Shelby GT350 will have the same coupe body as the regular Mustang but it will be a bit stiffer so that it is sharper on the track. The last GT500 had far tyres which were staggered as well as an aggressive hood that was vented and domed. This GT350 looks more like a regular 2015 Mustang with more normal sized tyres and wheels and no huge rear wing as well as a hood with no vent.
However, there are lots of add-ons to the body which make it seems as if the GT350 will be a track worthy vehicle in the same lines as the Chevrolet Camaro Z/28. The prototype seen has very little disguise, which means that it is easy to see what it looks like. There are lots of mesh covered openings and it has an aggressive look. In the grille opening there are two kinked barbs which looks similar to the Focus ST and the Fiesta ST. There is a large splitter on the front and each wheel has tiny canards ahead of it with think vertical slots behind each front wheel, which shows that the aerodynamics have been very well thought out. There are four exhaust pipes on the back which are coming out form a diffuser element which looks rather muscular. There are little winglets beneath the exhaust tips which do not occur on the GT500.