not sure what happened, but it is not just keeping the windows open. I have had several friends who have gone on african safaris and they tour parks in open vehicles like this:
A friend who went last year told me a pride was around the jeep less than 6 feet away and totally ignored them.
Apparently, according to the park employees, as long as the persons inside do not move or call out, the lions do not see them and only "see" the jeep. However, calling out is dangerous since a lion may attack once it realises there are actually people inside the jeep.