Ford Fiesta MPG observation

[SwampSurvivor]

Originally Posted By: tig1
Originally Posted By: J611
While I lived in OK used to drive to St. Louis, MO few times. Had the same powershift 6 speed ... got average 39.5 mpg on I-44. Tried most gas brands and different octane blends ... the difference was marginal.



There's no way a 6 MPG difference would occur by merely changing fuels.


It's only 15%. It would be the equivalent of going form 15 to 17 mpg.

 

[redbone3]

Originally Posted By: Rust_Belt_Pete
I bought a brand new Ford Fiesta with the 6 speed "powershift" automatic transmission.
I usually take a trip to Rochester area from Buffalo one a week to see friends and inlaws and their "collection" of German shepereds and huskies.

I filled up with my local no name gas station with 91 octane ethanol free.
Drove to Rochester on the I90 the temperature outside was 56 degrees and I averaged the mileage back and forth from buffalo to rochester and back on the I90.
With minimal passing and cruise control on all the time I averaged 43.5 mpg on the highway.

Next week I filled my gas tank with NOCO 87 octane 10% ethanol, It was pretty darn cold and there was a bit of snow 37-42 degrees outside.
Same story same road same trip same amount of traffic and passing. 37.5MPG


Mileage was taken on the same strip of I-90 with about the same traffic.
Going to do another trip this weekend and see how my mileage is.


It is a fact that ethanol contains less energy than gasoline. I would expect lower mileage.

 

[dblshock]

I'm going with the tire PSI after the cold weather set in.

 

[Rust_Belt_Pete]

Well well my tpms light went on today in the morning.

 

[Subdued]

Originally Posted By: Rust_Belt_Pete
No shell in Buffalo area near me that I know of.

I need to do more testing.
The owners manual says 87 and up, the compression ratio is 11:1.
That is a pretty high CR for 87 octane if you ask me, I think it might be more of octane function and not ethanol content.
Have to fill up with 10% 91 octane ethanol to find out.
Could it be the temperature that is a pretty big difference.

Around us it's hard to find top tier, Valero seems to be the most widespread.

 

[Rust_Belt_Pete]

Well I took another trip on the same long strip of highway this time 51 degrees average and I inflated all 4 tires to about +2 psi over spec.
My computer showed 46.5mpg.
This is not the actual mileage but what the computer estimates but it is a good relative number. As before cruise control on at 65mph all the time. This is with ethanol free 91 octane.
The tire PSI made the difference compared to last time.