How do I create an advanced car?

Hi, I’ve been programming on ROBLOX for a while now, but I’ve never fully wrapped my head around how cars work. I know the basic VehicleSeat, but i’m referring to cars such as the ones in Jailbreak, MadCity etc. I’ve tried understanding free chassis, but it’s kind of hard to understand everything from 1000 lines of code that I didn’t write… I also want to know if the suspensions are physics based, or is it rays being cast to determine the position of the wheels, If anyone could take the time to fully explain this to me, it’ll be very appreciated. Also this is my first time posting on the devforum, so excuse any mistakes.