Originally Posted by macatron
Wow, thanks for such a detailed writeup on your trip! The thing that interested me the most, though, was the large spike in MPG when you were running 93 octane. Now, I know that there is already a HUGE thread debating this already, so I am just making the observation. Although, I might just have to try a tank of 93 on my next fill to see how my Focus likes it.
Again, thanks for all of the information and pictures (especially).
Yeah, some of those threads are what piqued my interest. I figured that 2,000 nearly-all-highway miles in a short time span would be an ideal time to test it out. Unfortunately, that possibly screwed-up pump after the first tank threw a bit of a wrench into everything.
Still... as I mentioned in the one note, based upon where the fuel gauge was when I filled up and its consistency during the rest of the trip I'm inclined to think that I actually used about 6.8 gal as opposed to the 8.3 the pump ticked off. If that's true, then my two tanks on 93 would be 43.0 and 45.0 MPG.
I know I need more data before I can say anything one way or another, but it's interesting. Taking the rest of the trip on 87 into account, it looks like I managed 36-37 MPG on those tanks. So, using the least-beneficial-$-wise case...
- If it's a $0.30 to $0.40 difference per gallon (which comes out to +12% assuming Regular's $3.40/gal)
- The difference in MPG is +16% (37.0 vs 43.0 for nearly 100% highway miles)
...then filling up with Premium would still make sense.
Like I said, it's certainly not conclusive at this point but I'd definitely recommend giving it a shot for a tank or two and seeing how your car fares.