14mpg on 94 octane?

Are you sure of the amount of fuel you're putting in your tank? To get the calculation right, you need to start with a FULL, topped off tank and then do the same thing when you fill up. It's the only way to know just how much fuel you've used. I'm sure this is intuitively obvious, but it's just one more culprit to eliminate as a cause of your issues.

 

To add to the above, what is your typical driving, ie all/most city (lots of stop lights/stop & go) or mostly 50-60 mph highway, or 70+ interstate, or mixed city/highway/interstate?
If you're serious about accuracy, determine your odometer error (gps or 50 miles by mile marker). Do not consider speedometer - it probably is off a different amount compared to odometer.
Last variable as mentioned above is accurate gallons. If you don't want to fill to the top, you really need to average 4-5 tanks.

 

It might. Go to one of the tire size comparators and see what the difference in size your bigger tires are from stock. For instance, my 275's are 5.2% larger than the stockers. If I went 200 miles according to my odometer, my actual miles traveled is 1.052 times the odometer reading or actual 210.4 miles. Obviously, the larger the tire, the greater the difference.

 

Urban legends. The gasoline octane rating or 10% ethanol content wont have any measurable impact on mileage for a 2nd gen Tacoma. Doesn't matter what you think you feel while driving, what anyone else says, or the mileage you think you documented. No need for a poll, a call to the Myth Busters, or a 100 tank year round test. Just do the math. Its very easy.

 

If I stick to strictly highway and 70mph I get 19.0-19.5mpg with even 85 octane (regular at CO altitudes) and 10% ethanol. Manual trans, 265/65/16 tires.

However driving around town even 50% of the time that drops to 16.0 mpg pretty quickly.

 

My best is 17mpg. If I drive over 70 it gets 14.

 

My google machine has spoken great wisdom with few links. I need to fill up and am going to do so with regular gas and see if I find any difference. My butt dyno has always told me 94 feels better. So I'm going to lie to myself an pretend I have filled up with 94 but use 87. I'll post results when I'm close to finish the tank

 

Yeah I drive mainly city stop and go

 

I did a couple of trials over the years switching from 87 to 91 octane and I don't think I saw any statistically significant difference. Driving style has more to do with fuel economy than any other factor. My FJ1100 (for sale if anyone interested) will get nearly 50mpg if I baby it around, or it'll get 28mpg if I ride it like a typical douche bag crotch rocket power ranger.

 

Here is what was said at coffee this morning. If you buy premium fuel and it has an octane rating greater than 91, it contains alcohol. So you might try a couple of tanks of alcohol free premium and see how you do, at 91. In my neighborhood one station sells premium at about 60 cents per gal higher that is alcohol free at 91, the other station sells premium for about 40 cents more, but that has alcohol at 93. (Also there was a big discussion about top tier vs non top tier gas, top tier being much better.....google top tier but what it means generally is the fuel sold at "major" brand stations, at non name brand stations there is often a "top tier" decal on the pump if they are selling top tier gas.)

Just what are you trying to accomplish? If it is more mpg carefully measure with 87, then 91, then 93 octane and see how you do with 3 or 4 tankfulls each, I fill mine to the auto click off then manually add 3 more click offs. In my 2013 6 cyl at 36,000 miles I get no measurable difference between any of the above, I live in Missouri, but when I travel thru New Mexico and Arizona sometimes the octane is 85, and still no difference......it runs tank after tank on that 3200 mile round trip generally between 19.3 and 22.1, mostly in the upper 20's, lower 21's. I attribute the difference to wind, amount of mountains, use of cruise control, distance between fill ups, load factor, etc. I have found I do better with cruise control off, where I can coast up hills, keeping the engine from downshifting, and accelerate down hills, and run no more than 5 mph over the limit. I still have the original equipment stock 16 inch tires, Dunlop AT20, 245X75X16. For an access cab, 6 cyl, 4 wh. drive, somewhat of a load am very satisifed. Often have a buddy that caravans with me from Tulsa and back in a full size 2011 Chev. Silverado 2 wheel drive V8 with cylinder deactivation that consistently gets less MPG than I, it just pisses him off......

 

You got an issue with you calculator? Or do you never drive over 50?

 

I charted my mileage using Low, Mid and High grade fuel and got the worst mileage with the highest octane fuel. Mid grade saw minimal increase in MPG. I use low strictly. I'm currently running 100% gas. It's 50 cents more per gallon, but gas is low right now so I'll see how it does.

 

Absolutely when the pump clicks off I can put another 2 gallons in no problem bottom line the tank is not full.

 

100 octane no alcohol is $4.49 gallon at the local air field do you think I should use that?

 

In the summer time I get 18 to 20 with 87 dose any one really think I would get enough improvement to make up the difference
in price?

 

Ethanol does lower mileage, no myth.
Automatic vs manual is different.
4WD is heavier even though we are in 2WD for the test.
265/75-16 will slow the odometer 5 miles for every 200 shown (ie. add 5 before dividing by the gallons ).
My 2010 V6 Auto 4WD gets 15-18 on California gas. If I drive slower, I can get up to 20, never more!

 

By exactly how much for E10? Show your work. For extra credit demonstrate that the measured difference under real world driving conditions can statistically significant.

 

Do not use Avgas in your truck.

 

I did the same thing with my tacoma except i went from 87 to 91. I did this for a few tanks and was getting worse mpg with the higher octane. 87 octane was consistently 18-19mpg. 91 octane was 16-17mpg. All same driving style and same driving route.
I think this has alot to do with that these engines are built specifically for 87 octane. Once you run many many tanks of 87 octane, switching to a 91 octane with different supplements and additives will change the combustion of the fuel. Since 91 is used more specifically for high compression engines to prevent pre-detonation its really unecessary to run 91 in these engines. But then again im not a professional. Hope this helpes.

 

If memory serves me correct, I recall the first 2 or 3 years of the 4.0 Tacoma requiring the use of Premium Fuel.