Flex Fuel

Hi All,

I have a question about my Flex Fuel gas mileage. For some odd reason, when I put flex fuel in my Exp (yes its made for flex fuel) and I do it to try and save money on gas when I am in CA for work as the gas prices there are ridiculous. But, when I do, I get way less mileage on a tank of flex fuel then I do regular gas. Of course that then defeats the purpose of having a flex fuel vehicle. In reading about flex fuel, vehicles that accept flex fuel are supposed to get much better gas mileage with that gas on top of the big fuel savings. Mine gets about half the mileage on flex fuel than what I get with putting regular fuel in. Everyone I have asked so far (mechanics and people working at places like Pep Boys, Autozone, etc.) have no clue. Most have no experience or knowledge about flex fuel vehicles it seems. If anyone can give me information about why I am having this issue and if there is anything I can do to fix the problem, would greatly appreciate it.

Source: https://www.fueleconomy.gov/feg/ethanol.shtml

E85 (Flex Fuel)
E85, also called flex fuel, is an ethanol-gasoline blend containing 51% to 83% ethanol, depending on geography and season. Summer blends tend to have more ethanol while winter blends have less.4 E85 can be used in FFVs, which are specially designed to run on gasoline, E85, or any mixture of the two. FFVs are offered by several automakers. We provide a brief guide to help you determine if your vehicle can run on flex fuel.

MPG. Due to ethanol's lower energy content, FFVs operating on E85 get roughly 15% to 27% fewer miles per gallon than when operating on regular gasoline, depending on the ethanol content. Regular gasoline typically contains about 10% ethanol.5

Cost. The cost of E85 relative to gasoline or E10 can vary due to location and fluctuations in energy markets. E85 is typically cheaper per gallon than gasoline but slightly more expensive per mile.

Performance. Drivers should notice no performance loss when using E85. In fact, some FFVs perform better—have more torque and horsepower—running on E85 than on regular gasoline.6,7,8

Availability. More than 2,800 filling stations in the U.S. sell E85. Visit the Alternative Fueling Station Locator for service station locations.

Dawgbyt said:

Hi All,

I have a question about my Flex Fuel gas mileage. For some odd reason, when I put flex fuel in my Exp (yes its made for flex fuel) and I do it to try and save money on gas when I am in CA for work as the gas prices there are ridiculous. But, when I do, I get way less mileage on a tank of flex fuel then I do regular gas. Of course that then defeats the purpose of having a flex fuel vehicle. In reading about flex fuel, vehicles that accept flex fuel are supposed to get much better gas mileage with that gas on top of the big fuel savings. Mine gets about half the mileage on flex fuel than what I get with putting regular fuel in. Everyone I have asked so far (mechanics and people working at places like Pep Boys, Autozone, etc.) have no clue. Most have no experience or knowledge about flex fuel vehicles it seems. If anyone can give me information about why I am having this issue and if there is anything I can do to fix the problem, would greatly appreciate it.

Click to expand...

Its all about energy density. Pure gas has more energy per unit of measure than gas with ethanol in it. So, to do the same amount of work, you have burn more fuel.

Basic physics.

Jeremy W said:

MPG. Due to ethanol's lower energy content, FFVs operating on E85 get roughly 15% to 27% fewer miles per gallon than when operating on regular gasoline, depending on the ethanol content. Regular gasoline typically contains about 10% ethanol.5

Cost. The cost of E85 relative to gasoline or E10 can vary due to location and fluctuations in energy markets. E85 is typically cheaper per gallon than gasoline but slightly more expensive per mile.

Performance. Drivers should notice no performance loss when using E85. In fact, some FFVs perform better—have more torque and horsepower—running on E85 than on regular gasoline.6,7,8

Click to expand...

About that cost......E85 is not cheaper than gasoline (per gallon or BTU or any other measure). The price you pay at the pump may less than that regular gasoline right next to it, but since ethanol is subsidized by federal tax dollars, you (and everyone else) pay the difference in your payroll tax deduction. Ethanol fuels are more expensive than pure petroleum fuels. The difference in gas pump price is the magic of legislation meant to change the behavior of a populace.

About that performance: Tell me how a substance with a lower energy density can produce more power than a fuel with a higher energy density. Its a physical impossibility.

bobmbx said:

About that cost......E85 is not cheaper than gasoline (per gallon or BTU or any other measure). The price you pay at the pump may less than that regular gasoline right next to it, but since ethanol is subsidized by federal tax dollars, you (and everyone else) pay the difference in your payroll tax deduction. Ethanol fuels are more expensive than pure petroleum fuels. The difference in gas pump price is the magic of legislation meant to change the behavior of a populace.

About that performance: Tell me how a substance with a lower energy density can produce more power than a fuel with a higher energy density. Its a physical impossibility.

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I won't argue with you on the performance... The info I posted above is straight from the fueleconomy.gov website. If you read down to the pros and cons they say exactly what you say about performance, they just gloss over that the lower energy only correlates to lower gas mileage.

bobmbx said:

About that performance: Tell me how a substance with a lower energy density can produce more power than a fuel with a higher energy density. Its a physical impossibility.

Click to expand...

Geez I can't explain it very well and I'm not even sure this addresses your question but ... If an engine is designed and tuned for the ethanol fuel it can deliver more hp & torque. That's why some race engines use ethanol fuel. I believe ethanol has a much higher octane rating and can support higher compression ratio. You can cram more fuel into the cylinders and get more power out but the whole engine system and cycle has to be designed for that. From what I've read there are EcoBoost Expy tunes that capitalize on this and make the 6000 pound tanks go faster with E85 than with gasoline. Am I incorrect?

Stock 5.4L Flex Fuel V8 makes both more hp and torque on E-85 (320 Horsepower/ 390 lb ft) vs 310 Horsepower/ 365 lb ft on 87 Octane gasoline. It advances timing on E-85 and therefore makes more power.

I know 5Star offers both 87-93 octane and E-85 tunes for the 5.0 & 5.4 and yield impressive results.

JExpedition07 said:

Stock 5.4L Flex Fuel V8 makes both more hp and torque on E-85 (320 Horsepower/ 390 lb ft) vs 310 Horsepower/ 365 lb ft on 87 Octane gasoline. It advances timing on E-85 and therefore makes more power.

I know 5Star offers both 87-93 octane and E-85 tunes for the 5.0 & 5.4 and yield impressive results.

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More power but less MPG, because more fuel is needed volume wise to yield the same amount of energy.

Some vehicles do see a performance decrease though when running E85, because the PCM can only correct but so far, and with less energy per gallon, equal fuel rates will yield less power.

That is where after market tuners come in. They tune specifically for ethanol. More power, but less MPG regardless.


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bobmbx said:

About that cost......E85 is not cheaper than gasoline (per gallon or BTU or any other measure). The price you pay at the pump may less than that regular gasoline right next to it, but since ethanol is subsidized by federal tax dollars, you (and everyone else) pay the difference in your payroll tax deduction. Ethanol fuels are more expensive than pure petroleum fuels. The difference in gas pump price is the magic of legislation meant to change the behavior of a populace.

About that performance: Tell me how a substance with a lower energy density can produce more power than a fuel with a higher energy density. Its a physical impossibility.

Click to expand...

You are a bit misguided or haven't been educated quite enough. Yes, E85 is subsidized however you can not compare E85 to 87. It should be compared to 93 or higher octane. E85 (really E70 plus) will allow you to make more power than 87 and 93. The properties of ethanol allow for higher resistance to knock and it's cooling ability. Yes you burn more (9.8 parts air to 1 part E85 vs 14.7 parts air to 1 part gasoline) but you have a much higher octane rating (somewhere over 100, some quote 105 plus). At the end of the day E85 WILL make more power than gasoline, you simply apply more of it.

https://www.taxpayer.net/energy-nat...r-corn-ethanol-and-other-corn-based-biofuels/

Holy cow, this place is loaded with engineers.

If effeciency is your agenda, stop looking at cost per gallon. Determine your cost per mile. Its not physics, its not petroleum engineering, and its certainly not a one-size-fits-all. Its a simple mathematical trade off.

And for what its worth, its been my experience to never take any automotive advice from anyone working at Autozone or Pep Boys. Its like asking the drive thru worker at McDonalds to recommend a Zinfandel.

Have a look at the current E85 station map:
https://afdc.energy.gov/fuels/ethanol_locations.html#/find/nearest?fuel=E85


I'd probably get real-life E85 info from somebody who lives maybe the upper midwest? Looking at the map I see E85 isn't that common in AZ. Most who have heard of it probably are basing their facts off of propaganda they've read on the internet...