14mpg on 94 octane?

Back to Cars.com for Model Year 2008 which is what I had and it now lists Regular and just as the Salesgirl mentioned the previous 4.0 Tacoma required Premium. Hopefully someone with an early year can copy their Owners Manual and post it up.
http://www.cars.com/toyota/tacoma/2008/snapshot/

 

I downloaded a copy of the 05 Owners Manual and on page 254 it says for Improved Performance use 91 or higher Premium Fuel.

https://s3.amazonaws.com/otpc/manuals/2005-tacoma-manual.pdf

 

I get around 21 mpg highway and 15 just driving around hilly western Pa....87 octane gas for me

 

Okay, so I have a theory that I may have been getting bad gas. Wasn't filling up at the "good" places (Shell, Chevron, and the like) but I've been going wherever it's cheapest the past couple months without fail. Trying to switch over with the tank I added today, and I'll give an update when I've done a few fill ups.

 

I think your on to something here. I picked up my Taco used last month and have been getting 15-16 mpg running 87 octaine between city and highway with AC on. It seams like most guys driving this truck with stock wheels are averaging 18mpg. My truck has larger rims 17x8.5 vs stock which is 17x7 and 265-70R17's vs stock 265-65R17. I drive fairly conservative and in my last vehicle I always averaged above the stated mpg rating. I tried looking up the weights of my wheel set for comparison but couldn't come up with anything. I did contact the original owner who drove the truck for 8 years. He said the milage didn't change a bit when he changed the rims/tires and that he could improve 2 mpg's by running premium gas... Makes me pull my hair, I've been trying to figure out if something is wrong with the engine, bad spark plugs, dirty air filter, low grade fuel/oil. I'm thinking of doing headers, tonneau cover, and trading out my spare tire for a flat kit just to improve efficiency lol. even buy premuim gas. However without being able to measure anything my feeling is that I could get more bang for my buck by switching to smaller less agressive tires and lighter narrower rims or at least lighter and higher quality at the same size. I can say from experience as a cyclist that as far as the bike goes nothing makes a bigger performance difference than switching to lighter wheels/tires. On my Mt. bike. I even keep a seperate wheel set for race day vs trail day. I'm almost positive that there is a direct corolation between the percent wheel weight increase and the percent mpg decrease.

 

Mine is an 08 and the owners manual says to run a minimum 87 and "research" 91 or higher. Not sure where and how they expect me to research but based on an article I read on octaine ratings some engines can auto tune for higher octane. Maybe the 08 and newer Tacos can. Although one thing I noticed on the cars.com info was that the 05 V6 on premium is rated at 245 hp and the 08 V6 is rated at 236 hp, maybe running premium in the 08 could produce 245...?

 

There are 2 different ways to measure octane, 1. is MON (Motor Octane Number), 2. is RON (Research Octane Number). What you see on the pump these days is the average of the 2.
They are not telling you to research anything, it's just trying to clarify that what is required, and is sort of clear as mud.

 

The horsepower didn't actually change, just the way it was measured. The 4-cyl also dropped between MY2005 and MY2006, from 164 to 159.

 

Also keep in mind that because almost NOBODY buys 94, whatever they have in the 94 tanks might be really nasty guk instead of actual fuel.

 

Oh, I know this, I've been using 87. It was the OP who was using 94.

 

Yep, and I was adding on to your thought for the benefit of OP.

 

Actually I have 2 other cars and a motorcycle that require 91-94 octane as do many other people so at least where I live the tanks get turned over quite a lot.

 

YOU are NOT "everybody". You are just YOU.

 

Gotcha, thanks for clarifying. My brain doesn't function that well this time of day

 

I didn't say I was everybody, what I said had you read what I actually wrote was I have 3 other vehicles AS DO MANY OTHER PEOPLE (where I live)!

 

Most people DON'T have vehicles that want 94.
Those that do are typically going to the big brand name gas stations.

 

As I mentioned earlier, I did compare 91 Premium (nothing higher here) to 87 on an 800-mile trip. 400 one way using 91 and 400 back using 87. Almost 0 difference, slightly better using the 87, in fact.

 

I'd highly recommend investing an an Ultragauge. The real time MPG readout is super handy to keep tabs on your leadfootedness. I set mine to also show throttle position %. You'd be surprised at how a little throttle affects mileage. Sometimes when I'm driving the throttle % goes from around 25 to 30 and the real time mileage goes down like 3 or 4 mpg.

As far as octane, in the manual for my 2014 4-cyl it says that 91 was the "test" octane. I take that to mean that if I want to see the power/mileage claimed in the manual then I should use 91.

I remember way back when I had my old 91 I used to worry about it passing the yearly emissions test. I read a few places that running a tank of 93 would help the engine run a bit cleaner so I just started doing it all the time. May as well have it run cleaner all the time instead of just once a year! I carried this habit over to my new truck thinking it'll run a bit cleaner and more efficiently.

 

My engine seems to run smoother on 91 and I also notice a 1-2mpg better range while driving so I stick with 91 at 87 it sounds a bit harsh. I have a 08 tacoma 4x4 v6 auto with 35's