Okay, so maybe there is more than one benefit... One major benefit I noticed is that it saves the starter gear from wear since the starter disengages as soon as the engine starts. I walked out to the parking lot after work yesterday and heard three different non-push button cars starting. One Honda and two Fords. Each driver held the key for at least 1 or 2 seconds of grinding after the engine turned over. My mom does the same thing with her 2011 Honda Fit. Grinds the starter for a second after the engine has already kicked over. I just want to yell "Let go of the key!". Then there are those people who can't hear their car running and try to turn it over when it is already running! So +1 for push button starts in those scenarios.