MPG surprise after adding 10 gallons of E15

[jespersensteven]

I’m super confused now. Last night I drove over 100 miles home from shift and topped off my tank for the first time with E15 to see what the $.30 discount would translate to mpg wise. I was blown away to almost immediately see a difference on my gauge on the cluster. Usually I see a range of 22-25 when I’m driving 55 mph on the way home and end up back home with about 22 mpg average. This time I was seeing it fluctuate from 24-29 and higher at times and I ended the trip with a 27 mpg average. How could this be possible???

2022 Ram 1500 Bighorn 3.6 etorque

 

[Sascwatch]

I know E85 will produce more power but decreased economy is the trade off. I would hand calculate your mileage to make sure the truck isn’t confused and adapting to the higher ethanol content. Most fuel is already E10, changing to E15 shouldn’t make much of a difference.

 

[djevox]

Yep

I know E85 will produce more power but decreased economy is the trade off. I would hand calculate your mileage to make sure the truck isn’t confused and adapting to the higher ethanol content. Most fuel is already E10, changing to E15 shouldn’t make much of a difference.

Just like sascwatch said, the higher the ethanol content, the worse the gas mileage should be due to the stochiometric differences between gas and ethanol in the combustion chamber. I could write a book about that, so it’s probably best to Google that for some fun bedtime reading.

 

[ferraiolo1]

The jump to 10 to 15% e won’t alter the mpg that much. Especially 10gal.

E15 is all I run and my mpg hasn’t gone up or down compared to 87/89

 

[jespersensteven]

Yep

Just like sascwatch said, the higher the ethanol content, the worse the gas mileage should be due to the stochiometric differences between gas and ethanol in the combustion chamber. I could write a book about that, so it’s probably best to Google that for some fun bedtime reading.

That’s what I thought, but was super confused by what computer was saying. Will see after todays trip and calculate at the pump. Here’s hoping it was true and somehow get that awesome MPG.

 

[djevox]

That’s what I thought, but was super confused by what computer was saying. Will see after todays trip and calculate at the pump. Here’s hoping it was true and somehow get that awesome MPG.

I have no idea what’s going on with your situation, but more mpg is never a bad thing

 

[HemiDude]

One heckuva tailwind??

 

[GKIII]

E15 has about 1% less energy content per unit volume vs E10, but the 88 octane doesn't hurt on the HEMI. BUT, it still shouldn't make a noticeable difference on your fuel economy vs regular E10 blends.

 

[Moosefire66]

Did they change it? My fuel door on my v-6 says I can't use the e-85 gas

Mine is a 2019

Sent from my SM-G991U1 using Tapatalk

 

[GKIII]

Did they change it? My fuel door on my v-6 says I can't use the e-85 gas

Mine is a 2019

Sent from my SM-G991U1 using Tapatalk

OP is talking about the E15/UNL88 blends you see at a few gas stations. E85 is off the table.

 

[HSKR R/T]

I’m super confused now. Last night I drove over 100 miles home from shift and topped off my tank for the first time with E15 to see what the $.30 discount would translate to mpg wise. I was blown away to almost immediately see a difference on my gauge on the cluster. Usually I see a range of 22-25 when I’m driving 55 mph on the way home and end up back home with about 22 mpg average. This time I was seeing it fluctuate from 24-29 and higher at times and I ended the trip with a 27 mpg average. How could this be possible???

2022 Ram 1500 Bighorn 3.6 etorque

If you were using E10 87 octane before, I could see a difference. But also you have to allow time for the PCM to adjust to the different fuel. I recommend three full tanks for the PCM to full adjust the adaptives to get a true indication of any difference the E15 makes

 

[jespersensteven]

Did they change it? My fuel door on my v-6 says I can't use the e-85 gas

Mine is a 2019

Sent from my SM-G991U1 using Tapatalk

It was the E15 that has 15% ethanol instead of 10%. After my trip today, computer is back to normal and still showing 22mpg average. Must have been the pc just being confused.

 

[Bigbags85]

Did the temperature go up while you were at work? I have noticed my truck gets way better gas mileage at temps around/above 45-50F.

 

[Rebel2022]

Did the temperature go up while you were at work? I have noticed my truck gets way better gas mileage at temps around/above 45-50F.

Yes I noticed this as well, quite noticeable. 0c and below (32f) is the worst, 5c (40f) and up makes a pretty massive difference. Never noticed this on my 4th gen.

 

[Bigbags85]

Yes I noticed this as well, quite noticeable. 0c and below (32f) is the worst, 5c (40f) and up makes a pretty massive difference. Never noticed this on my 4th gen.

Yeah, I've never had a vehicle where I've noticed this much of a difference due to temps. Didn't really pay that much attention to this info when it was below 0F (and hopefully those days are done for the year haha) but I'm curious to see that info now.

 

[GKIII]

Yea, I've also noticed my truck gets WAAYYYY better gas mileage based on temperature. I used to attribute it to winter blend fuel but being in TX we get freezing temps and sunny spring days in the same 24 hour period during Feb/March. It's definitely linked to temp, like 2-4 mpg swing between freezing and warm days.

 

[CalvinC]

If you were using E10 87 octane before, I could see a difference. But also you have to allow time for the PCM to adjust to the different fuel. I recommend three full tanks for the PCM to full adjust the adaptives to get a true indication of any difference the E15 makes

This ^^^

E content sensors (or other sensors used to infer e content) take time to realize the e content has changed. I’d say don’t read too much into the dash reading and wait until you hand calc a tank or 2. Should be no difference, or slightly worse as you suspected.

 

[ferraiolo1]

Non flex fuel vehicles don’t have ethanol sensors.

That’s why you can only run up to e15 in these trucks.

You CAN buy a flex fuel conversion kit for these trucks that plumbs a sensor in the fuel line though.


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[eye exaggerate]

Aside: 22 mpg, lol, I’ve gotta figure those metrics - holy cow, I stay around 12 / 19L (was 8 in the winter).

 

[jespersensteven]

Did the temperature go up while you were at work? I have noticed my truck gets way better gas mileage at temps around/above 45-50F.

Temps were about the same, days later now and it’s back to where it was before. Averaging 20-22 mpg without towing. Hope it goes up in summer!