Fuel useage computer.

BOSMECH

BOSMECH

Member
I know everyone says the fuel MPG calculator computor is inaccurate all the time.
Well I do the old fuel math consumption (miles drive amout of fuel used by how much was added at next fill up) and it is pretty damn close minus 2% fudge factor.
My question is and another enginner is : If it was that much inaccurate I would think Toyota would have gotten rid of it before they got sued for false readings.
Whats your thoughts ?
Thanks BOSMECH
 
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I keep track of every fill up and note my actual gas mileage along with the dash display. My odometer is approx 8.5% off, I've figured that into my manual calculations but not the displayed mpg. Over my fillups for the last two months, the display has been off anywhere from .025 to 1.945 mpg, with an average error of 0.899 mpg. When using the uncorrected mpg, the display has ranged from 1.17 to 3.14 mpg off with an average error of 2.213 mpg.

I don't have logs from when it was stock so these are not excellent statistics, but it'll give you an idea. I do remember it always being at least 1.5 mpg optimistic in stock form, just don't have actual data from back then.
 
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I just use it as a general idea of mileage vs an exact value. If it drops suddenly from 19 to 15 I'll know something is wrong with my truck (or someone swapped my v6 for a v8). Other than that I just ignore it. I also am pretty good at just not caring about my mileage. I consider the gas I use driving my 4runner to be half entertainment expense and half fuel expense.
 
I hand calculate mine every time and it is always reading 2.5-2.7 MPG high. I actually do not pay attention to it other than to make sure it doesn't take a big drop.
 
there would be no case against toyota b/c they never state that MPG will be garunteed. they are average readings and may vary. not to mention, you would have to include all the other major car manufacturers in the lawsuit as they all have a MPG gauge which is never accurate.

heck, GM even went as far as putting in a "dummy" coolant gauge in most vehicles in the 2000's b/c people would complain that their vehicle would run too hot etc...so they said ok, put in a set prefix for the gauge and it stays at a certain temp all the time regardless..bang, no more complaints even though nothing changed with the engine or coolant systems.
the factory gauge on my T/A reads 210 degrees all the time...no matter what (and i actually logged it reaching more like 220-225 in stock form). now i have a 160 degree stat in it, electric water pump and bigger radiator.... the temps rarely touch 200 degrees...yet the gauge still reads 210.
 
ARK_SWAMP_RIDER said:
I keep track of every fill up and note my actual gas mileage along with the dash display. My odometer is approx 8.5% off, I've figured that into my manual calculations but not the displayed mpg. Over my fillups for the last two months, the display has been off anywhere from .025 to 1.945 mpg, with an average error of 0.899 mpg. When using the uncorrected mpg, the display has ranged from 1.17 to 3.14 mpg off with an average error of 2.213 mpg.

I don't have logs from when it was stock so these are not excellent statistics, but it'll give you an idea. I do remember it always being at least 1.5 mpg optimistic in stock form, just don't have actual data from back then.
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Thank you ARK_SWAMP_RIDER that does equal about 2% and that is what I callcuated also.
 
BOSMECH said:
Thank you ARK_SWAMP_RIDER that does equal about 2% and that is what I callcuated also.
Click to expand...

Not sure how you're getting that number. My average uncorrected mpg for that period I'd 15.36. Average error of 2.213 equates to roughly 14.4% off. My average corrected is 16.66 mpg. Average error of .899 is roughly 5.4%. Either way, still over doubleyour number.

However, it's still not exactly relevant due to the mods.
 
My display has read 1-2 mpg high since new, same with my 2011 Avalon. I have tried resetting it many times and it is always off.
 
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ARK_SWAMP_RIDER said:
Not sure how you're getting that number. My average uncorrected mpg for that period I'd 15.36. Average error of 2.213 equates to roughly 14.4% off. My average corrected is 16.66 mpg. Average error of .899 is roughly 5.4%. Either way, still over doubleyour number.

However, it's still not exactly relevant due to the mods.
Click to expand...

Mine is bone stock.
 
If you drive a consistent route all the time....you'll find the gas calculator to be somewhat accurate.

HOWEVER....if you're like me where some weeks all I do is drive to work...and other days I'm going to work..plus I'm shuffling my son to and from a BB game or soccer game...or going camping...then I find the calculator to be way way way off.

The algorithm is just not accurate enough to give a useful reading.
 
I am 100K miles into our 4Runner and it has never been close to accurate. It consistently over states the MPG by 2 to 2 1/2 MPG. How it is driven has not made any difference. I don't really pay attention to it anymore other than to verify it is still off by the same amount. I like my FJ much better in this regard as it doesn't have the useless indicator...
 
Like everyone else mine is off by ~2 mpg's most the time. Which out of 20 is ~10%. Assuming i got 20 that's a pretty high margin of error. My GM cars were actually pretty darn close within about 1mpg and sometimes lower than actual. Just different algorithm used I guess...
 
interesting that the mpg computer is reliably 2mpg on the optimistic side
that tells me the algo is dang good, just that there is a fudge factor applied to make us happy with our mileage
 
Yep,
Mine is probably 2 mpg off to the positive side and I like it that way. The wifey don't complain about the mileage and she doesn't double check it manually :-)
 
Ya, i think its' way off.
But on a side not, I can now see why you guys in the south get better mpg with the v8.
I was getting 13.5l/100km on the comp during the winter. Now its 20 celc all day, comp dropped to 11.9/100km. And similarly when hand calculated. Amazing what difference temp can make.:wink2:
 
Well like I am saying is a well tuned and efficent machine will give you good mileage plus a light foot and knowing where to save gas at by coasting to stops and so forth etc. etc. etc.
But I have found the MPG computer to only be off by about 2 to 2.5 MPG.
 
I just completed a 2000 mile round trip and during that time the computer was reporting about 10% higher MPG than hand calculated.

Seems like the sweet spot was between 65-70mph. When I got up to 80-85mph, MPGs dropped to around 16. V8.
 
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