If we’re not getting further variants of the New Edge Ford Mustang, then I suggest adding their parts as customization options for the in game Ford Mustang SVT Cobra '03.
1999 Mustang GT - Front bumper, rear bumper, side skirts, hood and spoiler
2003 Mustang Mach 1 - Front bumper, rear bumper, side skirts, hood and spoiler
Pre facelift SVT Cobra - Front bumper, rear bumper, side skirts, hood and spoiler
