There have been a few times where I parked in the driveway after work but then wanted to move the car into the garage later at night because of possible rain or cold mornings. I usually won't make it into the garage before the ICE starts running. Since I don't know how much longer the ICE will be running before it shuts off automatically, I shut the power off completely. However, this causes the car/ICE to shudder very roughly. Is this actually bad for the ICE? Should I just sit and wait a few more minutes for the ICE to turn off on its own before powering down the car? Before I got the Prius, all my other (non-hybrid) cars never shuddered this roughly when I turned off the ignition but were always rather relatively smooth in this transition.
I just did this last night because a guest for dinner was blocking the garage when I got home. The ICE started up as I had to back up first before pulling in and it shut off without a problem when I pushed the power button. This is a situation I think we should be able to use the EV mode even if the ICE is not warmed up.
The Prius tries very hard to stop the engine at a particular crankshaft angle, so it's easy to re-start. When cold, or when you put in oil that is too thick, the HSD has trouble hitting the correct angle on the first try or two (or three, or four...). Hence you perceive a shudder, as it tries to "bump" the engine to the correct angle. It won't harm anything, other than your nerves.
Thanks for the explanation. That sounds logical although like you said, it does sound and feel very disconcerting each time. Maybe I'll just sit in the car a few extra minutes from now on until the ICE shuts off on its own first now that I just finished upgrading the stereo system.
