my fuel efficiency journey

lot of debate, and different results and numbers. i figured id cataloug what ive got going on on my journey.

1999 v6 3.4ltr taco, 3" billy lift with eibachs and expos. stock size 31x10.5x15 tires, and 350lbs of weights in bed for expo's.

general driving habits are smooth, smooth accel, smooth breaking, etc etc. not granny driving but still very reasonable. i shift at 2000 rpm, and if im in a neighborhood, like my own im in 3rd gear at 15mph which is roughly 1000rpm.

my daily commute 6 days a week is 40 miles, 39 of them are highway.



at 85mph i achieved roughly 15.5ish mpg with 87 octane. this is at roughly 3100rpm.
this is obviously not very good, as toyota rated my truck at 18. now this is roughly 215 miles till needle hits the e, 230ish till the gas light.

at 73 mph, which is roughly 2750rpm, i got 17.3ish mpg with 87 octane.
this is ALOT better.

now, on 89 octane, at 70 miles now driven, and 10 of those city streets cause of errands, ive used till the first tic. this is also not going over 73mph, smooth driving and so forth. when i fill up next i will report back on my mileage. but it feels extremely smooth and looks promising.

i MIGHT try 91 octane but thats gonna be expensive

 

I'm not refuting your empirical data but higher octane ≠ higher mpgs necessarily.

If your motor isn't high performance or turbo charged, then higher octane can actually be less efficient. This is what I found with both my Legacy and Tacoma.

I'm pretty sure they use detergents (among other refining techniques) to make the octane higher. Those detergents are not conducive to fuel efficiency.

I've been using fuelly.com, religiously, for a year now. I enter pretty extensive data into each fill up (octane used, if different, driving style, how much I used cruise control, temps for the week, etc..) and I've found that 85 octane yields just as good as mileage as 87 and better than 91.

The single most important factor I have found to increase fuel efficiency is the use of cruise control. I use cruise control as much as possible and after I made that switch I noticed a 1-2 mpg increase every tank.

 

When you say 85 is that ethanol? Can't say I've seen 85 here in the midwest.

 

We're stuck with lower octane fuel here at higher elevations.

 

I live in altitude (5,363 feet)

Higher altitudes require less octane.