Fuel Type - Ethanol's effect on MPG

The fuel I use on my 13 prius c2 sure affects my mpg. I drive in town and many short trips without warm up. I only have e10 fuel but the difference in 87 vs 92 octane e10, seems to worth the money to at least test it out. that is what I am doing right now. and with two tanks of 92 giving much better mpg than the 87. I will continue to switch back and fourth and see long term what I find out.

almost everyone will say that higher octane has no benifit in our prius, but I think very few of them have tested to see.

 

The Prius c engine has no parts in common with the Liftback, v, or PHV, and only about 30% in common with the Gen 1 and 2. While I doubt that if gets better MPG due to octane, even if it does, that does not mean that we did not test our flavor of Prius.

 

OK, here's a test for you. I get to visit VIR often and the last 8 trips were equally divided 4 and 4 between regular 87 octane and high test 91 octane fillups from Shell. Return trips using 100 octane unleaded track gas.
I found no signicant difference in mpg between high test and regular going to VIR. The mpg ranged from 45 to 47 mpg and involves about 20% suburban traffic and 80% rural. No interstate. And no attempt to maximize mpg. If you were in the way you got passed.
All 8 return trips were after filling the tank with 100 octane unleaded gas from the track just before leaving..
In every case mpg increased by 3 to 4 mpg even though the tank was never refilled by more than 4 galloons. Once arriving we refilled just outside the track with the same kind of gas to get mpg then ran one session with that gas and after refilling with 100 octane unleaded ran one more. MPG wasn't much different but top speed increased from 98 to 102 mph, a significant difference as expected for race gas. (incidently thoiugh the pump stated "up to 10% ethanol we didn't detect akcohol by test).
Each trip back on the exactr same route achieved 3 to 4 mpg better just on a less than 50% refill.
There is no doubt by us that the refineries process gas production to provide as much gas as possible and the energy pere liter of fuel is down from about 117,000 btu per lb to 112,000 btu per pound for either regular or high test though high test may be little higher but statistically not enough to garantee better mpg.
And non alcohol gas simply isn't worth the cost unless you competing in an mpg or racing contest. Just as you could epect. I wouldn't doubt the cost of processing is way hihgher than the price but then racing is important as marketing. And note too that all rfineries have differenct production formulas; just because we didn't find significant difference in regular and high test doesn't mean you won't. Next month we can get different resultrs than this month's.
good luck.
Got to talk to the rep; he identified the gas as no ethanol and a very special blend which is why it costs $8.85 per gallon,. Not surprised at all that the car seemed much peppier. We'll find out next week. Threy get 100 octane purely by the components without tetraethyl lead as required for highway fuel. Its a highway fuel like you don't get at your local pump.

 

OK Mahout great data but, if you have time, we need a little more details of where you filled up and everything. My area north VA is EPA RFG region, and they (Chevron) says in RFG regions the Premium is essentially equivalent energy to Regular because that's what the EPA regulations basically require.

But overall you are saying your data shows what I have also been trying to say: it is possible that some Prius Chat members have access to higher energy content blends (such as E0 in some areas) that could show significant MPG incerease, above and beyond the E10 3% debit...your numbers 3-4 MPG on a half tank is 6-8% more MPG on a half tank, which equates 12-16% more MPG on a full tank assuming we can ratio it. I'd be afraid to put a full tank of that stuff in too, but I hope to do some similar tests later this summer (when i get out of my EPA RFG region).

Where's VIR maybe I stop in.? Also next time you go to the track get us some MPG vs. tire pressure data (if you have time of course).

 

VIR, or Virginia International Raceway is close to Danville but about 20 miles east and barely before the NC line at Milton, VA.
I don't know if you can get in when VIR is oopen with only gas as the reason.
You may note as an old refinery engineer I have repeatedly and often stated that gasoline is a number of ingredients and ethanol is one nowdays thanks to hapless politicians and EPA refusals to permit more refinewries. The ingredients can be changed to yield higher combustion heat and naturally decreased with ethanol because its heat of combustion is a lot less than iso-octane, the model component for gasoline though there are dozens to choose from based on the distillation of the crude. Every source of crude is different - and processed differently.
Gasoline supplieed to racetracks especially ones forumulated for showrrom stock and mildly modified cars need to offer as much combustion heat as possible and naturally costing a lot more. And though klabelled as permitting ethanol I doubt it. There are a lot of components that have combustuion heats greater than iso-octane. And if you want to see just how much compare heats of F1 gas with pump gas and teyare eticformulations thatre nrgt posionous too.
One thing I should have dione was measuresay 40 to 70 acceleration times with station gas compared tio 'race' gas; but in rampnig onto I40 I notice a considerably faster gauin in speed on the race gas mixed with high test. How I would love to see Toyota add a turbo to the Prius C. Now that I'd buy in a heartbeat and I bet a lot would also. The Porsche 918 super hybrid is fine but the general car people need one more. C'mon Toyota, especially now since the Prissy is based on the Mazda 2.

VIR, or Virginia International Raceway is close to Danville but about 20 miles east and barely before the NC line at Milton, VA.
I don't know if you can get in when VIR is oopen with only gas as the reason.
You may note as an old refinery engineer I have repeatedly and often stated that gasoline is a number of ingredients and ethanol is one nowdays thanks to hapless politicians and EPA refusals to permit more refinewries. The ingredients can be changed to yield higher combustion heat and naturally decreased with ethanol because its heat of combustion is a lot less than iso-octane, the model component for gasoline though there are dozens to choose from based on the distillation of the crude. Every source of crude is different - and processed differently.
Gasoline supplieed to racetracks especially ones forumulated for showrrom stock and mildly modified cars need to offer as much combustion heat as possible and naturally costing a lot more. And though klabelled as permitting ethanol I doubt it. There are a lot of components that have combustuion heats greater than iso-octane. And if you want to see just how much compare heats of F1 gas with pump gas and teyare eticformulations thatre nrgt posionous too.
For northern VA check summit point WVtrack for you.
One thing I should have dione was measuresay 40 to 70 acceleration times with station gas compared tio 'race' gas; but in rampnig onto I40 I notice a considerably faster gauin in speed on the race gas mixed with high test. How I would love to see Toyota add a turbo to the Prius C. Now that I'd buy in a heartbeat and I bet a lot would also. The Porsche 918 super hybrid is fine but the general car people need one more. C'mon Toyota, especially now since the Prissy is based on the Mazda 2.

 

better gas will give you better mpg, its just a fact. like if you are trying to get a child to put on weight and you give them skim milk they aren't going to gain as much weight as they will with whole milk.

 

Haha, weird comparison. Pretty different but people probably get the idea.