First 2026 Ford Mustang Shelby GT500 Integrated Prototype Spotted Testing

Back in late February, a document surfaced online that was purported to be a communication between the United Auto Workers (UAW) Local 600 union and its members. That document was particularly interesting because it specifically referred to the impending addition of an afternoon shift at the Dearborn Engine plant in preparation to build more supercharged 5.2L V8 powerplants for the 2026 Ford Mustang Shelby GT500, signaling that this particular model might be primed to make a comeback. Now, Ford Authority has spotted what may very well be an integrated prototype of the new GT500 for the first time.

When we say integrated prototype, we mean that the major elements of the vehicle program, primarily the powertrain, suspension, and chassis, are being used here.

This potential 2026 Ford Mustang Shelby GT500 prototype was spotted wearing Dark Horse badging, interestingly enough, as well as camo donning its rear flanks. However, there are quite a few differences present here when compared to the Mustang Dark Horse, such as a modified front fascia with a large air intake on the driver’s side (the passenger side continues the Dark Horse fascia). Regardless, we see a set of massive radiators peeking out from behind the revised fascia – one at the center and another behind the driver-side lower fascia. Also present are a set of wider wheel arches and fenders, and in this case, a sticker placed right behind the Dark Horse logo – of a mule, humorously enough.

Perhaps even more interesting is the fact that this 2026 Ford Mustang Shelby GT500 prototype / “mule” is also equipped with the same exact wheels and 305/30ZR20 front/ 315/30ZR20 rear tires as the S550-generation model, though in this case, they’re Pirelli P Zero R tires rather than the Michelin Pilot Sport 4S rubber present on the prior GT500.

Also worth noting the presence of what appears to be a roll bar just behind the front seats.

It is currently unclear if we are actually looking at the rebirth of the GT500, however, as The Blue Oval has been mulling the idea of using a different nameplate for its future range-topping pony car, as Ford Authority exclusively reported roughly one year ago. However, the aforementioned UAW letter’s authenticity was later confirmed by the Detroit Free Press, via a source familiar with the program itself. Regardless, Ford has filed a variety of trademarks that could also preview this future model’s nameplate as well – including Boss, Dark Horse Boss, and Cobra.