I'm sure there are already threads on this, but I couldn't find anything worthwhile. But anyway... If I am just running into a friend's house for about 5 minutes in a very safe neighborhood, is it better to leave the car on or should I turn it off? My thinking was leaving it on might allow it to skip a couple warm up stages that it might otherwise do. Thoughts? Thanks! Stupid side question...can you leave it running for a little while but still take the key with you?