The Kawasaki Mule
It's a small tough 4x4, with room for three at a squeeze in the front or more in the back and a stash box in the front. It's road legal and small enough to get up most tracks or bridleway ways. Meaning if you riding local you can drive to the spot and then up the hill. Whats more is an oil burner, so if want keep your green credentials you can fuel it on veggie fuels. With space in the back for boards, kit and peeps. It's pretty much the mountainboarders skidoo. Also if your crew wants to travel in comfort you get a 4 seater still with a pick-up for boards and shizzle. What more could want.
Probably a roof and a windscreen but if you are going and getting muddy who cares anyway.