The other morning after stopping @ Tim Horton's for a coffee on my way to work (I'm in toronto this week) the idea hit me. My car is a manual so holding a cup of coffee, shifting and steering can be done but it gets to be quite a balancing act, I looked at the Small Square Box of Scott's tissues that I had Velcro'd to the left hand corner of the passenger floor mat and said hey it looks like a cup would fit in there. And Viola! it fits almost perfect. Now make sure the box is less that half full and you will have to reach over and just kinda hold the top of the cup while cornering but hey it worked pretty good.
Just thought I'd pass the idea along. It's not the fanciest and probably would not be good for a long distance (hmmm I'll try that on the way home) but for a short jaunt around town it works, and if you do spill anything you'll have tissues right there to clean up with.

Gary