There’s 1000 and one ways to do this even within chaos physics. The thing is as 2 cylinders or as 2 spheres is pretty much never going to be stable.
Even with 3 (a trike) it’s going to fall a lot, which is why the industry standard is to make a car that functions as a motorcycle - with which you custom fake all interactions.
I figure the guy just wants to learn for the purely academic aspect of things.
Re the cost of a cylinder, I think it’s simplified to just check the general area of a box of the same diameter first, then do a secondary check if a hit is there for the actual Pi variation.
That’s how someone sane would code it… but then again the new system is called Chaos, so…