Gundark, I, too, would like to see Biel, but I don't think that she's even being considered anymore. She was early on and I liked the idea. Alas, I don't think it's gonna happen. Both Simpson and Spears are bad for the role, IMHO.
And I'm glad they don't have Paul Walker cast because then it would just become a deep south Fast and the Furious. I also don't think Walker would be a good fit with either Knoxville or Kutcher. They wouldn't mix well in my opinion. Scott would work well with them, personality wise, and if he were to be a bit more serious (kinda like he was starting to be in The Rundown), then I think it could work. You need some humor in this, but not the outlandish humor that Scott is known for. He could still make it work though.