I know what you mean about the Elephants becoming acclimated to the vehicles in the parks. I once watched a 80# + bull feeding withing 50 yards of us for over an hour. On the other hand, on a photo excursion in KNP, on two consecutive days, we had our truck chased off by younger bulls. Both of these bulls came at us from a long distance (over 150 yards), and they were mad. Now I should also mention that they were both in musth, and my P.H. friend who was with me felt that they both probably had a loosing tussle with older bulls, and were run off by them, and so they were looking for something to vent their anger and frustration on.