A while back there was a thread on Taco gas mileage. Someone suggested that filling up with higher test gas could help improve mileage.(Something about the octane sensor advancing and giving better performance.) I gave it a try in my 07 six cylinder with manual tranny. I normally run the cheapest regular. So I bought a tank of Plus. Three hundred miles later the gas milage was the same. This time I filled up with premium. Today I filled up again. No Change. So after about 600 miles with higher octane, in my truck the grade of gas makes no diference.
Plus isn't what's recommended in my manual, but Premium. My copy of the book says 91+, gas pumps in my area say "Plus" is 89. I can't get
91, so I run 93 or 94, depending on the brand. As a data point, all of my local gas has 10% ethanol year 'round.
I'm going on three years of data, with only two missing tanks, that says 93 is a few pennies cheaper per mile than 87 in my '05 V6 4x4 manual shift Access Cab. This includes cold winters, hot summers, 4wd use off-road and in the snow, as well as towing a 3000 pound woodworking trailer (and a 5000 lb. blown-up Volvo, once ), and traveling with kayaks, 12-16' boards, and ladders on a Thule Xsporter overhead rack.
I did my comparisons with at least 5 consecutive tanks of each octane, allowing enough time for the ECU to adjust, and to average out filling errors, weather, and driving needs. Some folks reboot the ECU, but I've never bothered. The actual math (miles driven/gallons used) is done on each tank, as reading the odometer with the low fuel light, or other non-math methods can suffer from temperature effects and a lack of sensor precision. I fill the tank 'till it stops automatically, and restart the pump once more. My initial comparison was done with
10 consecutive tanks of each octane.
I get no difference in my 4 cyl. Subaru Outback or my wife's 6 cyl. Wrangler, but neither of them recommends premium fuel.
On a side note...
The truck pulled that Volvo on a 4 wheel trailer really well. The trip was 200+ miles through some Berkshire hills, stop and go city streets and rolling suburban terrain on a 75F day. Stopping the unbraked load was also better than I expected, trailer brakes would have made it barely noticeable.
With the computerized fuel injection electronic whizzbangs on new cars it shouldnt make any difference on octane rating. carburated it will and should be diff..
This information is meaningless unless you provide the actual numbers. Not to mention that this is irrelevant, since premium is not recommended for the 07 V-6.
If premium is no longer recommended, then all that should be obvious. That's why I mentioned MY manual, relating to MY exact vehicle , and the year of said truck.
On the other hand, if premium is not recommended, then it shouldn't make a difference.
But back to the original test... _Two_ trials does not make a very good test.
Always happy to show my work! Here are my numbers from the last 10 tank trial, done in 2006, starting with ~12,000 miles on the truck:
I pay $.19/mile for fuel to use $3.00/gal 87 octane I pay $.19/mile for fuel to use $3.30/gal 93 octane
For the same price, I'll take the performance using the fuel recommended by Toyota engineers for my specific vehicle.
My historic high tank is 19.2 MPG, on 93 (the only time I've broken
19), the low 12.02, also on 93. The low tank contained a decent amount of towing in snowy conditions 4WD, the high was a decent length highway trip limited to ~ 55 mph by traffic. I normally drive ~ 70 on interstates, but the truck usually does mostly local trips, hence the low end of the EPA range.
20.3 mpg average on 31 tanks from day one, 2007 double cab V6 automatic, 48% highway, 52% city (my city not bad stop and go), all on
87 octane regular, no ethanol, best tank 23.6, worst tank 18.2, premium not recommended so won't go there, have a bed cover seems to help marginally, I drive conservatively.
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