Premium Gas and Better MPG

Bottom line is premium gas won't give you better mpg unless your engine can use the increased timing. And the timing increase is only really used under wot. Most people who switch to premium for mpg increase will see it, because they change their driving style during that time. The drivers right foot impacts mpg way more than anything else.

 

That sucks, I live a couple miles on dirt roads. I have heat shortly after I leave my driveway (assuming 10-20 seconds of warm up time). By the time I hit pavement I'm at full temp. My mustang otoh, I'm half way to town before the needle moves.

 

Run a comparison calculation to compute your miles per dollar, not miles per gallon.

 

I just recently topped mine off with 91 octane after running 88 octane for the last 3 months. I have noticed a definite improvement in throttle response and power. As far as mileage is concerned I haven't noticed a big difference there but I drive differently from time to time.

 

I've swapped back and forth between premium 91, mid grade 88 and regular 87 since I've owned my 2004 4 cyl. 4X4 for the last year and my experience is just like yours. I can't really put my finger on it and the mileage seems to be about the same but my truck just "seems" to run better on premium and that is the case even at the higher elevation where I live which is around 6600 ft and at least 4000 ft wherever I travel. I do run a lower octane in the winter sometimes. But I see no difference. When it comes to mileage it's hard to tell because I drive different depending on where I'm going at how much time I have or whether I'm out driving around on dirt roads and climbing for a day. All in all the premium does seem to work better. By today's standards the 2.76 is a somewhat high compression engine.

 

Fyi, the 1GR was designed to run premium but is able to retard timing for lower octane fuel.

 

Less interest in a truck when you open the gas door and see premium only, at least thats what my 08 fj had.

 

the 2.7 is only a 9:1 or 9.5:1. There's nothing earth shattering about it. And x compression = y octane doesn't really apply as octane requirements vary on actual need, elevation, temperature etc. Sea level and hot weather, standard is 87-89 the high octane is 93-95 I think? Up where I am you can't find above 91 and standard is 85.

Requiring high octane is a safety net for the manufacturers. If you require the highest available the odds of a user suffering damage from detonation is low. Kind of like requiring everyone strap on a parachute all day every day and carry a life raft decreases the odds of falling out of an airplane unprotected and then drowning in an ocean. It doesn't matter that a vast majority of people don't need either, as the odds for the few that do have drastically improved.

If you're not racing/towing/abusing the engine you won't make any more power on high vs low. Although studies have shown that running a higher octane in an engine that's not performing as it should will reduce output and mileage.

 

Definitely in your head. I one-upped you, and tried switching from 87+ethanol to 91 pure gas in the winter. Objective was to see if running the pure gas made enough of an impact on fuel consumption to justify the higher price. It didn't. In fact, it didn't make any measurable difference at all.