The higher octane will not help mileage unless you are rattling on 87.

 

thanks for replies!

9T6AvalonXLS, car seems running OK on 87 fuel, but I feel it does have less power on hard acceleration, especially from dead stop.
What bothers me is that I used to see higher MPG numbers with mostly highway driving in past (different highways, different areas, less traffic though) than I do now ... in past I was running 91/93 fuels ... now for sakes of my wallet I switched completely to regular 87 (with 10% ethanol in NJ).


pmesfun, LOL, same reason here why I switched to regular only too ... crap world ...
I am still wondering if I do have some issues related to slightly lower MGP or it's the recent driving patterns (crappy traffic mostly) being responsible for lower numbers and not 90%+ hwy driving (was around 30% city plus some prolonged idling) ...

Never noticed a difference, plus I can't afford premium anyway lol.

yeah LOL, I know that on-ramp woop feel with premium fuels LOL, regular fuel is weaker in that matter LOL... and yes, we are having some 90F+ weather since 2 weeks around here. I switched back to regular 87 (with 10% ethanol) just over 2 weeks ago ... kinda missing some ponnies sometime, but usually I don't notice any difference in driving ...

So, the MPG shouldn't suffer from regular vs premium fuel switch, good to know.

Thanks for input people!

I'd just think over the physics of this question. 1. Within the tiniest fractions measurable, 87 and 91 Octane fuel contain the same number of BTU's. The 91, is just less volitile or explosive. 2. The additional amount of power that 91 will make is from better ignition timing, not really in the amount of fuel sprayed and burned. 3. It would take a computer driving for you, to pull back your throttle inputs, just enough to simulate the same power outputs called for, from 91 to 87 octane levels, over any kind of a drive.

The 1mz-fe, has a much higher compression ratio than my old V-6, so I bet the performance difference on the 1MZ engine is much more than I see. I'll bet that on a really hot NY day, it adds as much as 10hp for the old on-ramp woop-up, but I've never seen anything that suggests it gives better fuel economy.

Little Edit: Sorry Fenixus, to be very specific about my "work logged" milage: I have seen no difference in fuel economy between the two fuels. The only thing that I have noted, was that I get significantly lower milage on 94' octane, ethanol enhanced fuel. Really quite noticable on the gauge, and about 10% lower by the numbers.

 

Never noticed a difference, plus I can't afford premium anyway lol.

 

I'd just think over the physics of this question. 1. Within the tiniest fractions measurable, 87 and 91 Octane fuel contain the same number of BTU's. The 91, is just less volitile or explosive. 2. The additional amount of power that 91 will make is from better ignition timing, not really in the amount of fuel sprayed and burned. 3. It would take a computer driving for you, to pull back your throttle inputs, just enough to simulate the same power outputs called for, from 91 to 87 octane levels, over any kind of a drive.

The 1mz-fe, has a much higher compression ratio than my old V-6, so I bet the performance difference on the 1MZ engine is much more than I see. I'll bet that on a really hot NY day, it adds as much as 10hp for the old on-ramp woop-up, but I've never seen anything that suggests it gives better fuel economy.

Little Edit: Sorry Fenixus, to be very specific about my "work logged" milage: I have seen no difference in fuel economy between the two fuels. The only thing that I have noted, was that I get significantly lower milage on 94' octane, ethanol enhanced fuel. Really quite noticable on the gauge, and about 10% lower by the numbers.

 

I'd just think over the physics of this question. 1. Within the tiniest fractions measurable, 87 and 91 Octane fuel contain the same number of BTU's. The 91, is just less volitile or explosive. 2. The additional amount of power that 91 will make is from better ignition timing, not really in the amount of fuel sprayed and burned. 3. It would take a computer driving for you, to pull back your throttle inputs, just enough to simulate the same power outputs called for, from 91 to 87 octane levels, over any kind of a drive.

The 1mz-fe, has a much higher compression ratio than my old V-6, so I bet the performance difference on the 1MZ engine is much more than I see. I'll bet that on a really hot NY day, it adds as much as 10hp for the old on-ramp woop-up, but I've never seen anything that suggests it gives better fuel economy.

Little Edit: Sorry Fenixus, to be very specific about my "work logged" milage: I have seen no difference in fuel economy between the two fuels. The only thing that I have noted, was that I get significantly lower milage on 94' octane, ethanol enhanced fuel. Really quite noticable on the gauge, and about 10% lower by the numbers.

The more you can advance the ignition timing, the more you can make the engine act like its compression is higher and make more power. It isn't just about heat potential. It isn't like burning a candle. Your 10 hp increase can translate to quicker acceleration which means shorter interval at that rate is needed to reach high speed. Shorter time is saving, since you can back off sooner. Knocking is a problem that is damaging and can be reduced by retarding ignition timing and making the engine act like its compression is lower and power potential is less than it could be with 91 octane, when you use 87. Rate of change was lost on everyone arguing this so far, and that has gone on and on and on. Next time you take a long trip on the highway and you use GPS, notice the ETA is one statement at the outset. That calculation assumes you're obeying the speed limit. However, if you beat the speed limit you will see the ETA get reduced- minutes start disappearing and that means since your trip is going to end sooner, you also stop consuming fuel sooner. To a lesser degree, when you cut the time of acceleration, there is saving there too. If we're going to conclude this in a practical way, we need to also look at more conservative driving style putting less demand on the drivetrain, but costing more time needed to make the trip. At any rate, while we sit a a red light it doesn't matter what octane or power potential we have. That's where MPG is zero, but on the other hand, any driving is going to burn gas to one degree or the other. Now it up to each one to find his own happiness.

 

recently I checked OBD2 on this car and was actually amazed how well all numbers looked like. total fuel trims (long term + short term) were pretty much within +/-3% on both banks, near perfect, and right after I pulled in the lot, one bank was actually perfectly zeroed out, while the other minimally negative (slightly leaner) - that is on regular fuel which means it's doing very well!

The front end brakes and suspension are pretty much perfect (lots of new parts over past 3 years) and I think it's becoming time to look into rear end at some point.

For starters I know the calipers over their are old OEM, never touched, just flushed and re-lubed slide pins, perhaps I will remove the darn busings from those slide pins too (were becoming a problem in front calipers on both cars, just a matter of time).
Last time I checked/touched rear wheels after driving, they were cold, need to re-check maybe something is changed by now (slightly dragging rear brakes or rubbing parking brake shoes?).

At least the wheel hubs were replaced all around on this car 2-3yrs ago, so at least I know that is not it.

 

Gonna pull this one back from the dead:hi:

so i was playing with my torque app and with the v6 solara 5 speed, on 87 octane my car was like driving a bus, really struggled in certain situations (like accelerating on hills). It was saying 25.6mpg combined town/highway long term average over a few days. When the low fuel light came on I filled up with 91 and after the same 3 day period of combined driving it clocked 32 mpg average. :clap: The extra cost of premium fuel doesn't seem like such a pinch now.

On another note, with 87 octane fuel, the timing advance jumped between +30 at a light cruise and would fall back into numbers like +2, +5 on acceleration, once it even went negative (retarted timing). Timing advance is nice and smooth (no constant/crazy corrections) and it gets into the mid +40's on the highway, down to 19 when i floor it.


so it cost me $93 dollars to fill my tank with regular 87, and it costs $105 to fill with premium (fuel prices, canadian, $1.30 regular 1.46 premium)

 

yes, my point of view is same. basically to maintain the same level of drive-ability you need to press the gas pedal harder on 1mz-fe running 87 fuels than you would when running 93 fuel, this and only this accounts for added MPG if driver maintains same routes and habits for comparison with other factors at constant.

I prefer 93 fuel too, however due to "savings" I've been running 87 in my automatic V6 since Winter ... time for a change soon ... at next refill, long trip in plans, will be actually visiting briefly the Canadian land for a few days

how much is gallon of 93 in Canada again? a hundred bucks per Camry/Solara tank, you say? wow! I think here it is around $60ish in NJ ...

 

I had the same thought as you about this question, so I tried it. I drive my car on the same route 5 days a week to work and back only about 45 miles round trip. The route is 10% city and 90% interstate. I didn't see any difference in mileage but could feel maybe a little boost in power but not enough for 40 to 50 cents a gallon difference.