And do you see or experience any improvement at all?
I'm mightily pleased with my MPG returns with my Outie and if I drive sensibly on side streets I manage to get 20mpg and on the freeways in ideal circumstances (no standstill or stop start traffic) I easily get 27+ MPG if I drive using the cruise control or with a light foot but I've read that I can get better returns on my MPG if I use a higher octane fuel. I use the lowest grade here in California but am considering using 91 every so often if it helps.

Anyone have any thoughts on this?

 

This is an old topic. It does not make a big enough difference to use higher octane fuel for a vehicle that does not need it. It would cause a richer fuel/air mixture which over time could cause build-up.

Unless you are doing something that is not stock like turbo/supercharger, or something that would cause different timing or hp needs, then there is no point to use anything than what is recommended. Which the outtie says 87

 

I use 87, and have topped out at 28.8 MPG. This was on a mix of some side streets and some highway.

 

I have gotten up to 30 mpg and only use 87 reg in my outi...!!!!!!

 

I use 87 octane. There is a QuikTrip station within a mile from my house and I prefer to use their gas because they are a top tier gasoline. Even though QuikTrip may cost a few cents more than cheaper brands it may save problems later on.

http://www.quiktrip.com/gasoline/toptier.asp

 

use NOTHING other than 87 octane.
you gain NOTHING using higher octane. The fact is, using higher octane than designed for can cause cold drivability issues, stalling, surging, and long term engine deposits.

use EXACTLY what is called for in all your cars. If it needs premium, use it. If it doesnt, dont.
very simple.

 

higher octane requirement is a hardware thing. if your motor doesn't support it, then using it will do nothing for it.

on my ES i used to get 32mpg on highway and about 27.5mpg in the city with stock tires. but i changed to 235/70 R16 and now i get 28mpg highway if i am lucky. haven't really been on a long enough trip to fully evaluate.