I find that if there's at least 1 other vehicle with you, you can hang back a few seconds and when he (inevitably) retreats I move forward and take over. This works well in a few ways, but needs "aware" players in hte absence of defined strategy Ususally the opponent will press his advantage, and I can get in a good few shots before he spots/targets/manoeveurs to get me. If you're lucky, your team mate will have got his attention, and you can sort of leap-frog
Not often it happens, but sweet when it does. Only tonight 3 of us (2 mob arillery and a tech) managed to deal with some khaki menace
Oh yeah, I also always retreat backwards coz I find it easier seeing the shots coming