I love this, it's delightfully silly. You really feel out of control, especially until you realize that you can't control your car or register bumping someone while a dialog box is up.
I did find that I could use a little strategy though, which kept it from being frustrating. As a hint to others going through this, you won't register your next collision on a colored car until after you close the dialog window, so if you wait to do so until you're near your target it can make things a little smoother since if you time it right you might hit them without you doing anything!
Excellent use of theme, nice work :)