You can have and drive *whatever* you want without any government interference.We'd also have National Reciprocity.
Minimal restrictions on configurations as well.
If I can own and operate, on public streets, a 1,300 hp Bugatti it would stand to reason I could also own and use a 30mm autocannon as well.
20mm, 23mm, 27mm, 30mm, 35mm or whatever degree of overkill suits your fancy.
Frankly I think a ballistic analouge for a Bugatti might be more like a 76mm Oto Melara rapid fire cannon.