new ork faq:
Q. Can Grotsnik board a vehicle if doing so will
get him closer to the nearest enemy than if he
moved normally?
A. In the spirit of the rule, if embarking in a
vehicle will not prevent him from charging that
turn and will also get him closer to the nearest
enemy than moving normally that turn, he may
do that. Once aboard, the vehicle must always
move in such a way as to move as fast as possible
towards the closest enemy and allow Grotsnik to
disembark and charge the closest enemy as soon
as possible
i would charge headlong with him and MANz in a battlewagon + deffrolla straight at the enemy anyways just to intimidate