There's an interesting article I think you should check out by Road and Track. I went to the library and looked into the archives to find some various magazine articles about XT6's and how they performed. I posted them up and one of the XT6 guys saved them at his site.
Road and Track article
I didn't post the whole article, only what made reference to the XT6's performance BUT your BMW is in there. It shows how it performs amongst cars such as the XT6, Justy, Toyota All Trac turbo, etc, etc. It's interesting! You can at least see the results of the test but you'll miss the details of your ride. You can always check the original articles as well as others of the time printed of your BMW. Hope this helps!