One problem related to speed control springs has been reported for the 2006 Toyota Prius. The most recently reported issues are listed below.
I found that there is malfunction on the buttons on steering wheel, especially info button and buttons for climate. I researched the problem on internet and I found the problem is caused by a bad clock spring. Also, I found the clock spring is related with air bag module. There are a lot of owners have the same problem (such as Priuschat. Com). I think that it could be a recall issue. And I experienced another problem. The accelerator pedal of my car was repaired by the recall service before. But when I release the accelerator pedal and try to push brake pedal, there is difference of height between both pedals. The height of brake pedal is higher than the accelerator pedal, even if I released the accelerator pedal. So it is dangerous to operate both pedals. When I tried to push the brake pedal after I released the accelerator pedal, my right feet was stuck with the brake pedal. I think the recall service for the accelerator pedal of my car was not successful. Or there is another problem on the brake pedal of Prius.