this is only my 2nd tank since owning the Prius. on screen, it averaged 55.8 and the fill up after was 9.4 gallons so 53 ish is actual MPG. however, i'm fed up with babying the gas pedal. i can't stand driving like an old man. i think i'll put up with a slight decrease in MPG in return for a "normal" driving habits. keep in mind, my previous two cars were STI and 04 M3. so it's a big change for me... on a side note, i just put in 91oct, i'm hoping 91 will give me better MPG, we'll see..
The general consensus is that higher grade gas will not yield better MPG. Since the Prius doesn't need it keep some change in your pockets by buying regular grade gas. I saw an article the other day that higher octane gas actually has less energy. Here is one reference through Google search: Octane and gasoline engines 4 Nov 2009 ... Secondly, higher octane fuels often contain less energy per litre, ..... So, to me, there is a benefit to buying higher grade fuel despite ... www.sindark.com/2009/11/04/octane-and-gasoline-engines/ - Cached
i drive pretty normal without babying the throttle, and doing 75-80 on the freeway and still have no problem getting 51-52mpg. those tanks were my normal driving tests. now i'm gonna hit up eco mode and see what i get.
