I have experienced the "cold start chutter" twice. Last night coming home from work (around mid 20's degrees) and this morning (low 20's). The evening was parked in a lot all day, the morning from home- an attached garage temps above freezing.

I've previously experienced slight chutter infrequently and randomly when moving from a full stop at a light, when the engine turns on, regardless of whether engine was warmed up. This was slight, and I assumed must be the nature of the hybrid. But these two cold start instances made loud rough noises from engine compartment, although quick (just a second) as the engine turned on, not when I press the start button. My wife standing at the garage door clearly heard it.

Obviously this raised my concern, so if anybody hears anything about this as being a real problem, please be sure to post it here!

Have the new car since Dec. 1st.