I've read in another thread, a while back, about prius owners experiencing their new 06 shudder after ice has warmed up. Many people casted it off as being the cold weather and that it's normal for car to shudder violently immediately after ice has turned off. And I'd agreed that it made logical sense. Yet, I'm experiencing this during warm temps (ie, 65+) while car is parked on an open parking lot and the inside of my car is baking (returning from work). Now, I don't know if the reason is that the car is new and needing time to break-in but it's been happening for quite a while. It doesn't happen as much in the morning (parked at a curb in front of house), when it's cooler, but it happens often when I return from work in the evening , after hopping off the subway. Any thoughts or suggestions? I have 450 miles on my car. Hope this helps.