Algodoo

I tried to fix the uncentered wheels but if they are still slightly uncentered let me know

I managed to use brakes mostly for the car instead of putting them only on the invisible boxes, so the crashes should be better now

There is, unfortunatly a cause on why the wheels still look uncentered: the suspension is bad

Make sure the springs are also centered on the "suspension box" (don't make the end point to the box too centered, just a bit above the axle) while building cars. To prevent the suspension from being too bouncy, increase damping. Daming reduces the "bounciness" of the springs. You can make the suspension "higher" by changing the "target length" into desired amount.