The FOURSIXTEEN was unveiled at the 2014 Pebble Beach Concours d’Elegance event, with the California-based manufacturer announcing it would be priced at $152,000 (£92,000) including the cost of the Tesla Model S P85 it is based on, but excluding local purchase incentives.

Saleen’s upgrades include a revised transmission, now featuring an altered final gear ratio to improve acceleration and a locking differential to increase traction off the line or while cornering. This is matched to a larger radiator, with new fans and a higher capacity water pump to keep the drivetrain cool.

The FOURSIXTEEN also includes a full aerodynamic bodykit to increase downforce, plus higher performance brakes and suspension behind Saleen-specific wheels and track-ready tyres. Its interior is awash with leather, carbon fibre and Alcantara, and features more supportive front and rear seats to hold occupants in place, as well as a redesigned centre console with cupholders and a storage compartment.

Owner Steve Saleen said: ‘Tesla has created an entirely new class of American automobile. There are many similarities to this and how Ford created the “pony car” class in 1964 with the Mustang, which is how these vehicles stand out from the rest of the pack.’

Saleen, an original equipment manufacturer which has been converting production cars to supercar performance for nearly 35 years and has competed in motorsport series across the world, can carry out the conversion in six to eight weeks, and the FOURSIXTEEN includes a four-year, 50,000-mile warranty.