When entering a vehicle like the V3S in first person, your head stays locked in one direction facing toward's the hood or front of the vehicle rather than facing the direction of the seats like it should.
Also for example I've noticed this bug has also been seen with the new vehicles that will be arriving in 0.59, at RTX 2015 Brian Hicks showcased the new vehicles which had also done the same bug. Link - { https://www.youtube.com/watch?v=RWgDSIKVZN4 } *THIS ONLY APPLIES TO THE V3S, AND THE BUS!