It doesn’t matter if a Mustang costs $34,610 or $325,000, they all start life the same way on the same assembly line at Ford’s Flat Rock Assembly Plant in Flat Rock, Michigan.
The Ford Mustang GTD is absolutely hand-assembled in many ways by the team at Multimatic, but it doesn’t start life that way. The reason? The supercharged track-ready Mustang shares its frame with the standard Mustang, along with nearly every hard point for the body.
At the launch of the 2025 Ford Mustang GTD Chief Program Engineer Greg Goodall told The Drive exactly how the GTD is built and brought to life. Here’s what we learned.
The GTD is built at Flat Rock like every other Mustang to the point of being a body-in-white, which means the frame and body surrounding it for the most part with the hard points are all assembled like any other iteration of the muscle car. Not present: most of the things that bolt on, including the fenders, hood, and trunk. The roof panel, which is normally welded or adhered in place, is also missing. Those components will be added later by the team at Multimatic, only they will be GTD-specific and made from carbon fiber.
It may be called a “body-in-white,” but each of the bodies actually leaves Flat Rock painted black. This is done to ensure areas like the engine bay all match for every car in a uniform manner.
The body-in-white, sans those missing components including a roof, is then transferred to Multimatic’s facility in Markham, Ontario, Canada.
The team at Multimatic then uses a plasma cutter and chops the body side off at the C-pillar (so they can later bond a carbon fiber piece to it), and cut the second-row seating area out so the suspension structure can be placed inside. Then a bunch of carbon fiber reinforcement is added to the base of the C-pillar area for the swan-necks for the rear DRS wing to ensure the structure can handle the aero loads put on the car. Additional structure is placed below that area in the cabin down low so the loads can be transferred without issue. That extra reinforcement is hidden beneath the black panel surrounding the lexan window in the rear bulkhead.
The rear floor, which would typically be the trunk floor of the Mustang, is chopped out with the plasma cutter. The Multimatic team replaces it with a flat floor, which is made of aluminum to manage the NVH (noise vibration and harshness) coming from the transaxle and subframe, both of which are bolted directly to the bottom of the rear floor.
Design Manager Anthony Colard said each sub assembly from the car, such as the gearbox, goes on a separate dyno before its put into the car.
Then Multimatic makes all the carbon fiber panels such as the roof, front fenders, hood, bond on the body-side outer panels, diffusers, and rocker panels along with the bumpers.
The GTD is then run through a paint system. From there the car, now painted, gets hand-rolled through 10 different assembly stations.
Ford builds the dashboard for the GTD at Flat Rock, but never installs them. The dashboards are transferred to Multimatic where the teams there install them with slightly different trim bits and GTD-specific software.
The 5.2-liter supercharged V8 engine starts at Ford’s Dearborn Engine Plant like all the Predator engines, but then it gets shipped to Performance Assembly Solutions in Livonia, Michigan, where it receives the dry sump system and a few other GTD-specific upgrades. It then gets shipped to Multimatic to get installed.
Goodall said a bunch of former GT 500 parts and current production Mustang parts, such an electrical architectures and modules, get kitted up and sent to Multimatic to be installed.
Bespoke stuff that gets sourced by Multimatic, such as the DSSV Spool Valve Dampers, or the Brembo-sourced carbon ceramic brake rotors, all get brought in and installed by the Multimatic team.
Once everything’s installed, Mustang GTDs get run through a “rigorous test schedule” Goodall said. This is to ensure all the software is functional, make sure all the features work, test it for water-tightness, and then put the car on a dyno to ensure it makes the power it’s supposed to.
Then the Mustang GTDs get delivered by a specialist to the waiting owners, but each customer is said to get a white-glove experience to ensure they are fully keyed in on the car’s features and systems.
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As Director of Content and Product, Joel draws on over 15 years of newsroom experience and inability to actually stop working to help ensure The Drive shapes the future of automotive media.
