This is an interesting thread that I just read through since it seemed to be popular enough to warrant 2 pages. I can vouch for DeWitt. He's an older regular and is over on bimmerforums to set the 16-year-olds straight about E28 M5 lore and what tasteful mods to put on their '92 525i with 230K on it.
I guess I'll keep my eyes peeled for one of these posters if it ever appears. Seems to be a pretty tight supply and a nice price in this market.
On my end of things (the E12 M535i camp) a guy on our M535i list scored an original, dealer promo poster over in the Netherlands where he lived. It was part of a large automobile literature collection and he got it for extremely cheap at an auction. Shortly afterwords, his BMW club had a trip planned to Mobile Tradition to see the car collection and he brought the poster with him. They had no record of it in their files but were very interested in scanning it for their archives. Unfortunately, an effort I made to have my own poster made from the 160 meg scan of the original (with Mobile Tradition approval I was told) was in vain because the scan was so good that it picked up discoloration in the paper due to the poster's age.
Here's the picture he sent to the list shortly after he bought the poster. It's a well known picture of the E12 M535i, but I had never seen it with the script underneath. It's roughly 36" by 24" he said.
