Regular or Premium gas?
#2
I only use 87 octane (regular) or 89 when that's all that's available. I've never tried premium because regular works just fine. I doubt a person would be able to measure the difference in MPG, unless MAYBE you were on a controlled track.
#6
use 87 every new engine with a knock sensor can run on 87 without any harm computer senses any ping or detionation and retards timing as necessary. Dont be fooled buy 91 only stickers. You will loose some performance but there is no harmful effect