I'm not aware of any pure platform available off the shelf, though I imagine a big enough checkbook and a conversation with Magna might get you pretty far, but you can buy from Ford the Mustang Mach-E motor https://performanceparts.ford.com/part/M-9000-MACHE
There are lots, but most are not road legal. All privateer racers in many race series use cars that are manufactured by established companies, then heavily modify them.
Alpine makes forks of BMWs.
Braubas makes forks of Mercedes.
RUF makes forks of Porsche.
The other example is when 2+ large manufacturers work together to cost share a platform.
Examples:
- BMW Z4 / Toyota Supra
- Subaru BRZ / Toyota GT86
- Mitsubishi 3000GT / Dodge Stealth
Several Aston Martin coupes were built on Jaguar platforms.
The NUMMI car factory in Fremont, CA was jointly owned by GM and Toyota before Tesla bought it. For a while, it made the Toyota Voltz / Pontiac Vibe.
I think people get the impression from the wording that the “platform available off the shelf” means the consuming manufacturer can just grab some units and modify them, but in practice, there is a massive contractual negotiation. And since car manufacturers are heavily regulated, it makes sense to cost share both the manufacturing and the standards / crash testing.
