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Built as a one-off vehicle, the Bill Shepherd Mustang F5 was designed especially for the Goodwood Festival of speed hill climb. The car began life as a lightning blue 2017 Mustang GT before under-going heavy modification and research and development in an attempt to build a car using after-market parts as foundation components. Following massive revisions by our team of Formula One and NASCAR engineers, we believe the F5 to be the most competitive after-market, road-legal Mustang that money can buy. The best bit? The car is a one-off, and now it’s for sale.

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In an experiment to test the viability of a modified Mustang at supercar ‘slaying’, we set out to test the waters on aftermarket performance components. After a number of tests we concluded that a Kenne Bell ‘Mammoth’ supercharger would be given the task of upgrading the Mustang’s power output. Once we had incorporated our own Bill Shepherd Mustang enhanced boost kit we found power output had increased by 300+HP.

We also went on and upgraded the exhaust system, including a Borla attak rear end. This not only improved exhaust flow but made it sound the part too. We had countless people approach us over the weekend and tell us how good the car sounded going up the hill.


We then tricked the car out with our own F1 engineer designed handling set-up including springs, dampers, anti-roll bars and geometry. Compiled with Bill shepherd Mustang specification high performance brake pads we saw significant gains in the handling of the car.


The car was fitted with an outlaw bodykit which included a chin spoiler, side rocker panels, ‘switchback grille’, decklid spoiler and high mount roof spoiler. We also had a set of double racing stripes and one-off F5 branded side-stripes applied in a 60s inspired Wimbledon off-white. To compliment the stripe colour we painted elements of the car (front pony, 5.0 badge, decklid GT badge) to match. We also made sure to paint the borla attak exhaust tips a gloss black in an effort to remove chrome from the car.

The F5 sits on a set of F1R 20” machined gunmetal rims fitted with Michelin pilot sport tyres.


Inside the cabin we replaced the stock steering wheel with the alcantara option GT350 wheel, along with a carbon fiber dash unit. We upgraded to a Hurst classic gear shifter, for style but also to help get hold of the shifter under heavy acceleration. The final detail for interior trim, a set of custom Bill Shepherd Mustang embroidered head-rests.


This car provides an exciting prospect to own a vehicle seen and coveted by millions around the world. Being a one-off, totally unique, Goodwood Festival of Speed performance vehicle, it’ll be the only one in the world, ever. Most importantly the car still retains all of its recognizably iconic festival of speed event stickers making it a real talking point wherever you go.