Mazda Skyactive octane/mpg

[circuitsmith]

Intake air temp and humidity have a significant effect on spark knock.
In hot weather (90+F) I found my Matrix runs "peppier" with 89 octane vs 87, but no noticeable difference in mpg's.
The price difference wasn't worth it to me though.
I suggest the OP try the octane experiment in the heat of summer.

 

[NateDN10]

FWIW, I have a lot more fuelups now and so I thought I'd revisit it. Long story short, the difference between premium and regular is still not significant at the 95% confidence level. I should note that I found a station with E0 91 octane which theoretically gives a 6.5% increase over E10 based on energy content, and I have adjusted the mpg values for premium as though they were all E10.

Here's the data:
Code:


regular premium

min 33.54 37.36

q1 36.4875 38.7112125

median 37.675 39.756025

q3 40.5925 40.007225

max 43.86 46.39


As far as cost goes, with 87 octane the cost per mile is 6.7 cents, while for premium it's 6.6 cents.

 

[L_Sludger]

I run 87 octane even in cars that demand premium just cause I can't justify paying $.60-$.80 extra per gallon. The price difference around here is unreal.