Well, I can only go by my own experience, I have three XMs, two'96 and one '95, none of them have any serious rust in them, I have two friends that I bought 405 diesel estates for, 95 and 96 respectively and they are near immaculate. My wife has a ,95 ZX estate and that has no discernable rust, they are all diesels if that makes any difference.
Peter
Peter