The Rocket Speedster Concept quickly becomes either a four-seat or two-seat convertible.

The carbon-fiber muscle car is a modified Mustang GT bolstered by aerodynamic body panels and a supercharged 725 hp V-8 engine.

It pulls out all the stops with 15-inch Brembo Gran Turismo high-performance brakes.

 21-inch, five-spoke alloy wheels match the car’s metallic-red finish.

Galpin Auto Sports and Henrik Fisker have blown the top off of conventional convertibles with the d…