It's water resistant.
It's fade resistant.
Heck, using my own $700 printer whose inks will last up to 80 years without fading if kept behind glass, haven't faded one shade since I printed the stickers for my car 10 months ago. (the paper's a slightly different color but the ink is the same.)
My new bumper sticker reads:
"My 1995 junkheap gets 28MPG.
How much does your 2003 SUV/Hummer get?
Was that big tax break worth it?
http://www.hummerteam.com/mpg.asp " (a link for them to not remember and use, hehehehe...)
My route to work routinely takes me across the path of not one but FOUR Hummer vehicles. A lot of SUVs too, I drive through the "Valley of the Neo-Yuppie".

One problem though. IBM markets these as 'temporary use only' and 'easy to remove'. That's a lie, the paper sticks to the car like desperate-man-on-hooker.