Real Gasoline, not Ethanol

Ethanol is a nice injector cleaner. Maybe those techs are showing you the results of using E85 in a car that isn't made for it; E10 on the other hand is perfectly safe in a Prius.

Under identical conditions E10 reduces MPGs by 3%. If you're paying more than an additional ten cents per gallon for that ethanol free stuff then it's not worth it.

 

That is the general consensus and all science backs it up. Gasohol has less energy than gasoline, so you will go less distance on the same amount (lower mpgs).

 

I would hope a 10% ethanol blend would not reduce mileage by 10%.

 

Yes if I were in your location I would also prefer no ethanol when possible. Ethanol is a political benefit not a scientific benefit for your vehicle.

 

We have 100% gas available here, but it's cost is about 25 to 30¢ more per gallon. My son & I both ran a tank of it......did not see the advantages that would warrant paying the extra for it. We are back to the 10% ethanol now.

 

Daryll, excuse me for asking a different question in your thread, it's just mine is related quality of gas, too, thought it might be helpful to some besides myself in here.

I filled up last week and sadly the pump shut off early (station was closing, or the bladder, not sure which). This week I was expecting a very low mpg number as typically follows a partial fill-up, but didn't get it. Instead I got a hand-computed average of 66.6 mpg for the two tanks.

Now, this is possible, but unlikely. The MFD read 67.2 mpg or so for those two tanks. My question is - if your fuel is of a better quality (these last two times I filled up at BP, advertising their Invigorate stuff, possibly better than others), does the Prius still calculate mileage the same way? In other words, maybe you get 60 mpg on the display, but if you got that with a crappy fuel, it may be 56 hand calculated, but with a good fuel it would be 59. Is that true/plausible/probable, or am I way off base here?

If these numbers continue, BP will probably get my business. If I get 55 on the next tank I'll pop in and let everyone know it was the bladder. I fill up rather slowly so that also seems unlikely. Who knows!

While some of you may want to provide technicals on the Prius calculation process, I'll kindly request that you dumb it down slightly for me as well

 

Smart move, that's a big price premium to get ethanol free. I don't know your exact fuel prices but I'm estimating its about 7 to 8 percent extra, and you wont get that back with extra gas mileage.

Most credible tests I've read show between 2% and 4% increase in gas mileage for regular (100%) gas versus E10. Personally I've measured only 2 to 3 percent (averaged over several tank) when I've tried to measure the difference in my prius. That's less than the tank to tank variation for most people, so you've got to be pretty careful to measure it, and it's easy to come to the wrong conclusion in one tank. I've seen people (self reported on the net) claiming outrageous figures like 25% improvements but I don't believe them for one moment.

I can still get regular (no ethanol) here and it only costs about 2% to 2.5% more. The net result is that cost per km is basically the same either way., nothing worth worrying about. I usually fill with regular because I just like to get the best possible MPG. Every now and then I fill E10 because I think it does help with injector cleanliness.

 

I agree, ammend my prior response to:
I would prefer to use E0 (no ethanol) if available and if the cost is no more than about +12 cents per gallon as Richard calculated.

I have seen no problems using E10, except lower mileage. I was certainly assuming in my metro-region, if I go to the outskirts I can get cheaper gasoline and without ethanol. Perhaps that is incorrect, not sure.

 

The Prius calculates fuel mileage exactly the same way regardless of what is in the tank. Even water would calculate the same way, although your mileage would be zero for obvious reasons.

All the Prius does is meter the fuel being used and measure the distance driven. The fuel metering is done by timing injector pulses. The miles driven comes from the odometer.

Hand calculation for a Gen II Prius (like yours) is useless for a single tank. The volumetric variation caused by the fuel bladder means you never really know how much fuel you burn for any given tank. The volumetric variation is on a per tank basis, so you can spread the uncertainty over many tanks and reduce its effect. If you total your fuel and miles over ten tanks the result is fairly accurate. Over five tanks it's not so good. One tank is useless.

Tom

 

Thank you, Tom, I appreciate the detailed reply, very helpful.

 

It would be really hard to do the comparison here since most of the pumps have a sticker that says "may contain up to 10% ethanol" so you don't know at those pumps what you're getting exactly.

 

Sounds like first time ethanol exposure, where the system is simply getting cleaned out by the alcohol content... because no one has problems like that here, where E10 is the only type of fuel we've had available for over a decade now.

Funny how the well proven still raises doubt... as we notice routinely about hybrid technology.
.

 

Well E85 is a whole lot more ethanol than E10. We haven't noticed E10 doing anything horrible to modern cars that are designed be able to use the stuff.

We were supposed to get "mandated" (by the government) E10 here this year and I wasn't looking forward to it - I prefer to have a choice. Luckily they've had to put those plans on hold because of a shortfall in local ethanol production. So I don't know exactly how long this "reprieve" will last, but for now I'm sticking with the ethanol free stuff for about 90% of my fill-ups.

 

I wish i could get real gasoline in illinois. Too much control by ADM and the corn growers loby. Now report of a problem at a chicago area refinery just in time for memorial day weekend and prices are reported to jump again in an already higest price area for gasoline. Looks like the prius wins again. I love my car lol.

 

From an energy content standpoint:

Gasoline: 114,000 BTU / Gallon
Ethanol: 76,000 BTU / Gallon
E10 is therefore theoretically: 110,200 BTU / Gallon, or 3.3% less.
E85 is theoretically: 81,700 BTU / Gallon or 28% less.

When gas is $4.00 per gallon, don't pay more than $3.86 for E10.
If E10 is $4.00 per gallon, be willing to pay up to $4.13 for pure gas.

 

The E-10 gas in my home area (Louisiana) averages (displayed):
47-48mpg summer
44-45mpg winter

A few months ago I discovered EF gas available in the area and get (displayed) 52-53mpg. The cost per gal is the same.

We took a long road trip up to Seattle and using
http://pure-gas.org/ tried to get EF gas as much as possible and had decent numbers except for one fill-up in Cheyenne, WY.

When we got to California on the return loop, where there are only five EF stations listed in the whole state on the above website, I resigned to getting whatever was near when we ran low. But even then the mileage stayed up around 53mpg. This continued on through AZ and NM. So, is the gas in those states (even with ethanol) better than what I get in Louisiana and surrounding states where historically I only get a summer max of 47-48 with E-10?

Some memorable lows during our yearly summer road trips, gas we got in Fargo, ND last year only got 42 and some in Cheyenne, WY that was supposedly EF only 40-41. Lower high altitude octane values haven't seemed to be an issue.

 

It wasn't the gas so much as the outside temperature and the headwinds.

 

Interesting website (pure-gas.org) Thank You. No EF near me Northeast, guess I need to move back to Louisiana. Now I am confused about why so many EF in Baton Rouge, I thought EPA had classified them as non-attainment a few years ago, even though the air quality is decent there.