Re: [toyota-prius] Mileage Report
> This May with the warmer weather I was expecting it to pop back up again but"E87" would designate a fuel that was 13% gasoline and 87% ethanol.
> my mileage was dropping to 48 per tank using E87.
Did you actually mean "87 octane"
> I tried moving up to E89 at the same gas station (Giant Eagle Get Go) to see if the octane rating would help the spark advance and got a consistent 52 mpg as result.An 8+% improvement in fuel consumption is NOT due to octane difference.
87 octane, 89 octane, 91 octane, and 93 octane pure gasoline each have the same energy content, varying primarily by volatility and perhaps tiny doses of additives and hence likelihood of pre-detonation.
Pre-detonation is known as "knock" which is why higher octane fuels are called "anti-knock", and recommended primarily when knock is a problem.
The octane rating, if the ethanol content is the same, and knock is not a problem, should make no difference to your fuel efficiency.
> And then the winter gas is not as good as summer mix."Different" -- yes.
"Not as good as" -- no.
Jim Saklad mailto:jimdoc@...
- Driving conditions make a big difference in fuel efficency - especially with the Prius and especially if you know some hypermiling tricks.
Sofar in over three years of driving my overall fuel efficiency calculated has been from 44 to 71 mpg depending on the overall driving conditions.
My (Scangauge2) fuel efficiency estimates per trip has vary even wider from about 11 mpg to 132 mpg depending on the driving conditions.
The Prius' HSI display fuel efficiency display estimates more optimistic .
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