Should I use premium gas in a 2015 Ford Focus SE?

[badtlc]

Originally Posted By: KeithS_NW_Ohio
Track your fuel cost using this spreadsheet. Do 3 or 4 fill ups with 87 and then 3 to 4 fill ups with 91-93 octane. The spreadsheet will show you your cost per mile on different fuels.
http://www.vertex42.com/ExcelTemplates/mileage-calculator.html


The only problem with that is it ignores weather impact. Weather has a very noticeable impact on MPGs.

 

[raytseng]

Originally Posted By: KeithS_NW_Ohio
Track your fuel cost using this spreadsheet. Do 3 or 4 fill ups with 87 and then 3 to 4 fill ups with 91-93 octane. The spreadsheet will show you your cost per mile on different fuels.
http://www.vertex42.com/ExcelTemplates/mileage-calculator.html


yea the problem with tracking MPG is your usage varies to widely.

Some people have graphed their MPG using even the same gas, and tank by tank; the MPG/tank sawtooths back and forth all over the place, even with a period of time of a whole OCI it's difficult to draw any conclusions.

 

[ExMachina]

Originally Posted By: raytseng
.
Some people have graphed their MPG using even the same gas, and tank by tank; the MPG/tank sawtooths back and forth all over the place, even with a period of time of a whole OCI it's difficult to draw any conclusions.


Unless they have just put in LiquiMoly MOS2 in the oil, then they suddenly see a whopping 20% increase in MPG !! Like weather, tire pressure, driving style, load has nothing to do with MPG.

 

[GiveMeAVowel]

ECUs are now sophisticated enough today that switching back and forth between octane levels we have today will cause NO issues.

This is one place where technology is a very good thing, the timing maps will perfectly adjust for the octane levels we have today. Like others have said you need to use several tankfuls of each specific octane before you will know how the car will perform, but the main reason the Focus, and Fiesta will respond positively to premium gas with higher octane levels is because the ECU software was designed in Germany and the predominate octane levels are typically at least 93 RON. Which in the Fiesta and Focus engines will provide much crisper throttle response, and slightly better MPGs it does increase HP levels about 7 or so from 87 to 93.

 

[TiredTrucker]

GM flexfuel vehicle's ECM adjusts to the new octane and ethanol mixture within the first 7 miles of vehicle operation after a fill up. I have filled with different blends and octane ratios fill up to fill up and never had any problem. Do have a pretty good record of what each fuel provides for economy, year round. So i just follow pump pricing on all the different stuff and fill with what gives me the lowest cost per mile at the time.