Tongue in cheek, fingers on keyboard.
Blues Brothers Class (but with a less collectable bodystyle):
Vehicle must be a 1991+ Crown Vic. Used Police and Taxis only, proof of past owner required.
Any pushrod engine up to 5.8L or OHC engine to 5.1L.
91 Octane only.
No nitrous, supercharging, etc.
3 Speed *or more) automatic trans only.
No quickchange or GV.
W,Y or (Y) tires only. Must have legal amount tread.
A 4x4 (3.5") must pass under car at any point.
Car must be street legal with all working lights and OEM side mirrors.
5,000 max raceweight. (naked is 4000 OEM).
This is not serious, but I just wondered how you'd cap spending, and still go pretty fast safely on 4 wheels. Antiques are $$$, Classics are $$, and homebuilt is $$$$.
The car model is proven safe with lots of crash data and airbags, and automatic fuel shutoff. Car is hard to flip (yeah, I tried before, it slides) and built like a Panzer with modern aero and excellent brakes.