Here in NSW Australia they've just phased out regular unleaded (without ethanol), so now the choice is premium (without ethanol) or E10. The regular unleaded that I previously used was just the 87 octane stuff (actually it's called "91 RON" here, but same thing as "87 AKI" in the US see : [ame="http://en.wikipedia.org/wiki/Octane_rating"]Octane rating - Wikipedia, the free encyclopedia[/ame]). Now I'm trying to figure out if I should just use the E10 or whether to switch to the preimum 91 octane stuff (actualy 95 RON = 91 AKI). The premium stuff cost approx 11% more so it's probably a waste of money, but I've never been much of a fan of ethanol blends. Which one to choose ???
If it was not a Prius, you would take about a 3% 'hit' for E10. Ethanol has 70% of the energy as gasoline. Sadly the Prius seems to be tuned so that ethanol and the butane in 'winter' gas are treated as filler. So expect a 10% hit on E10.
Yeah I did try a few tanks of E10 once a long time back and it seemed to get fewer MPG. Since then I've just used regular unleaded. The E10 used to be 2% cheaper but it actually cost more when you factored in the fewer MPG. Now there is no other choice for regular (as E10 is the regular unleaded now). What about the octane rating. I read somewhere here that the higher octane fuel is not good for the prius. Is premium 91 (95 RON) ok to use?
Whoa! What's that like? Using 100% gas, I mean. Sorry, but all we've had available here since the late 90's has been E10. That has meant suffering with an average of only 50 MPG. .
I would say about 1/3 of the stations around here still offer 100% gasoline and I use these whenever possible. Given the option between premium and e10 for the Prius, I would use e10 and not stress over it.
Since I first posted this I've found out that I can still get petrol without ethanol (for now). Several of the larger companies have gone to selling only E10 already, but there's still some independent operators selling it without ethanol. I was given some misinformation at one petrol station about when the "mandate" was to start. Unfortunately though it has been mandated (by our state government) that by July next year that all regular grade petrol (gas) has to contain 10% ethanol.
It's hard to believe a modern engine would waste available fuel as just "filler". Is there any documentation on this claim?
The important word in that quote is 'seems'. Every winter we get winter gas and reported Prius gas mileage plummets, many owners have reported E10 as having 10% less range than E0 gas. Many cars do well on E10, taking about a 2% to 3% hit on MPG, as they should. Prius owners see more of a hit. One of the major changes in 'winter' gas is more butane, so it starts easier. The Oil Drum | Refining 101: Winter Gasoline
