As I understand it, unless the vehicle has 0 value remaining, you must charge vat on it when you sell it on. In all honesty this is a complete waste of a conversation. Anyone who is vat registered will have an accountant. The best thing to do is call them and get the advice. My poor accountant gets several of these phone calls every year from me.
Not sure if this is true as I've seen vans for sale which have said the van has no vat to pay. I might be wrong though.