As a consequence of the 1.16 fix to wolves and bears being able to attack players in vehicles (T135495) they can not hit players in a vehicle with no (or open) doors.

This is of course just as bad as them hitting you in a closed vehicle. Make the presence of a door a condition for the player inside being eligible to hit, otherwise you just trade one bug for a worse one... This should of course also apply to infected. Ruined door should count as no door for this pourpose.

This would also make completing the car with all doors something practically useful rather than purely cosmetic.