Hey guys hate to start another thread about mpgs but I was just curious if anybody has actually compared different fuels and the mpgs they get.

For instance running 90 octance ethanol blended fuel vs 90 octane 100% pure gas.

Does higher octane help at all with mileage??

My hemi will never taste 87 octance from what ive read on this site.

This will be my last thread on mpgs. I love my truck and love rotties and both are literally chewing a hole in my wallet at the moment haha

 

this is on a 4.7

87 octane with 10% ethanol blend: 14.2 mpg complete city driving with o/d off

e85: 11 mpg complete city driving with o/d on

as of right now e85 actually costs more to run than normal gas

 

Stock, I got the same mpgs with 89, 91, and 93 octane.

10% ethanol takes away 0.5 to 1.5mpg from 100% gasoline in my Ram

With Diablo 87 tune, I got same mpgs as stock with 89, 91, and 93 octane.

Diablo 93 tune, 93 octane fuel, get about 1.5 mpg better than stock.

HemiFever custom 93 tune, I average 2mpg better than stock, and much more fun to drive.

 

With a tuner, I always got around 2-3mpgs better running the 91oct gas with the performance tunes vs the eco tunes and 87 or 89. So in the end the cost was about the same between the two, but I got to have more fun with the performance setting over the eco setting. Never really tried one vs another without the tuner though.

 

Octane by itself has little to no affect on mileage. However, real gas vs. the ethanol-contaminated stuff will take the vehicle less distance on a gallon of gas due to to less energy per gallon.

 

the ethanol is actually a higher octane, so like Mike said, its not a factor. Some engines are designed to run on it, and thats another story.

Like mike said, with ethanol being 70-75% as efficient as gas (the most realistic estimate), you are going to lose about 3-4% of your mileage. Not 1.5mpg difference @an average 14mpg.

Its been cheaper for me to run e85 as per my estimates, but the station is far off so I only get it when I drive by. But I cant give you a number because i have no idea the equivalence. I havent recalibrated my speedo after changing tires.

 

The numbers given out by the EPA are pretty much regarded as pretty accurate in relation to MPGs and Ethanol.

EPA estimates a 5% loss of fuel economy if using a 10% ethanol blend and about a 25% loss if using E85 in a vehicle equipped to do so.

I run a 100% 93 octane in both my truck (Superchips 91 Performance Tune) and my Grand Cherokee (4.7 HO engine which recommends 91 octane fuel or higher) most of the time. I find I get about 1.5-2 mpgs better with the pure gas than when using a 10% ethanol blend which would mean I'm finding a bigger loss of fuel economy with ethanol than EPA estimates...

 

I'm getting better mileage on the 87 eco tune, then I get with the performance tune.But thats because, I drive like richard petty with the latter; tune and octane.

 

Everyone keeps saying they are getting a ridiculous change in mileage with 10% but I just cant see it dropping that much. 2mpg is a significant drop when the thing gets 14mpg, so thats quite a big difference.

The EPA estimates are closer to what Ive been getting. Of course, my overhead averages me out at 8-9mpg with 40city/60hwy

 

My mpg's increased, after the fluid changes, and added modifications....ie; cai, exhaust. New spark plugs as well. Fuel really didn't enter into it, mainly cuz I can only get diff. brands, but they all are 10% ethenol.