Still haven't had the opportunity to measure the X5 & X6 running boards. But the more I look at the pictures (plus think of my experience/impression getting out of the X6) the more I think that the running boards are smaller.

http://www.xbimmers.com/forums/showthread.php?t=141018

The ones in the picture of the X6 look like the dots are closer together. And that the outside is straight from front to back. The ones on the X5 kinda curve outwards (in front) and back inwards (in back).

Really think it would be cool if those fit on the X5. Easier access in and out of the car while getting the looks of the running boards.