Pal, the whole point of the UN is so that the boss can drive a big Merc. They all have them (or huge Land Cruisers) so they can go from "meeting" to "meeting" in sufficient style in famine areas to impress the locals/dying/employees/donors that they are so hugely useful.
There is a book you should read - Lords of Poverty - Amazon will send it to you, read it and see if you want to be involved in this obscene charade of "aid work".
Been there, did it, threw the medal down the long-drop latrine where it belongs.