Build a two-door, rear wheel drive 6-speed car with the 2.0L EcoBoost engine that's very basic and inexpensive, but infinitely customize-able for enthusiasts. Then sell toys for it - a turbo, suspension components, crate Mustang V-6 engines that will fit. Think Civic/Miata hybrid, but infused with Mustang fun. Build it and you won't be able to keep up with demand!