Regular... Super... for our first week or two I did not have any idea about what Octane to use (I never gave it a thought or asked and I did not bother to look at anything.) I just did what I always did, I would pull in, and use regular. About three or so weeks ago I discovered that I should use 91 Octane. Hey for what little gas my little Bee use's, I have no problem putting in the Super. My point is this; we have been getting mind blowing gas mileage, using reg and Super. I do not see or feel any difference what so ever. Say what you want, believe what you want. If it cost me $.72-$1.20 extra a tank full I see no problem what so ever. (If it cost me $5.00 more I feel the same way.) My little bee is good to me, so I can splurge a little for its internals. Hey with a great car like this, with the mileage it gives us, why would you want to be stingy with it? It is good to me so I can be good to it.