Not policy, but some elders/COs thought from God's mouth to their lips...........
A family member started regular pioneering and bought a good car within his limited range, 2 doors....yes many 2 door cars are cheaper than 4-door.
One elder tried to enforce his personal policy on him...and was brought down on that by the congregation overseer who had just purchased a 2 door car himself.
If they can't show you in writing....it ain't policy...of course there are always "special" elders and congregations that have their own rules.