Spy photographers got a great look at what they believe is possibly a test mule for the next-gen Ford Mustang Shelby GT500. The vehicle is a heavily modified version of the next-gen model.

In front, there's a new front fascia with styling somewhat similar to the Dark Horse model. The separations in the upper grille are also like the mean trim. A wider front track pushes the tyres beyond the wheel wells. This suggests the production vehicle would have wider wings/fenders to cover them. The lower side sills look wider than normal.

Gallery: Ford Mustang Shelby GT500 Mule Spy Photos

The rear wheels appear to be carbon-fibre pieces. The ones in front have a black, seven-spoke style.

At the back, there are quad exhaust tips. The design makes the inner outlets slightly higher than the outer ones.

This development vehicle uses the Mustang convertible as the basis for the modifications. This might indicate Ford is planning on offering a droptop version of the hotter model.

It's not clear when this hotter Mustang might premiere. We wouldn't expect to see it this year because the initial 2024 models begin arriving in dealerships later this year. Ford needs to fulfil the demand for them before adding more variants.

The Dark Horse is the range-topping Mustang at launch. Power comes from a naturally aspirated 5.0-litre V8 with tuning that takes the output to 500 bhp and 418 lb-ft of torque. The transmission choices are a six-speed manual or a 10-speed automatic. As an option, there are 19-inch, single-piece carbon-fibre wheels that are 37 percent lighter than the standard ones.

Ford boss Jim Farley hinted in a tweet about the possibility of building a road-going version of the Mustang GT3 race car. If the model actually goes into production, it would likely be a track-focused variant with aggressive bodywork like a big front splitter, extractors in the bonnet, a rear diffuser, and a big wing. Suspension and braking upgrades would likely be part of the package, too.