Has anyone else calculated to see if the computer reading gas mileage on the center dash is accurate? I've calculated the last two tanks and compared to the computers, and I came up with it it being just over 1 mpg off. I showed 1 mpg lower than the computer was telling me. I searched to see if this had been discussed but didn't see it. If it has, sorry for not finding it.
computer gas mileage
- Thread starter toy94x4
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Yeah, the computer's too generous. Mine was off by 1.5 to 2 mpg (about 9%) for the last three tanks of gas.
I suspect that if you do the same driving and actually get the same mileage all the time the computer would eventually become more accurate, just as the range calculation seems to.
I suspect that if you do the same driving and actually get the same mileage all the time the computer would eventually become more accurate, just as the range calculation seems to.
V8Limited4wd
New member
mine has been consistenly off around 2mpg
DarksideSurf
New member
I don't trust the computer MPG anyways. Figuring how many miles I can get out of a 21 gallon fill up I'm getting 15.7 MPG. The computer spits out 18-19 MPG. With the manner in which I drive I'm not all that surprised though.
Man, I've been making a concerted effort to drive less aggressively to hopefully conserve gas. But I'm still only getting 12.4 avg mpg according to the computer. I hope it's due to me living in the city and never being able to go more than a couple blocks without hitting a traffic light or stop sign.
exokomp said:
Wow, that's a little low. With my V6 I got an average 21.5 mpg on a recent roadtrip, mostly freeway (tho the computer said 23.5 mpg) and consistently get about 15-16 around town, even in this city where stop signs apparently breed like rabbits.
Have you done a calculation based on gallons of gas/mileage rather than using the computer? Perhaps your computer's figure is too low for some reason.
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sharp4runr
New member
4WD or 2WD models get different MPG so post up what drive train you have when posting your numbers so we can figure that in.
Light_Mania
New member
I just got 20.6 mpg (423 mi/20.5 gallons) with the computer showing 22.5 mpg. I really soft-footed this tank of gas to see how high I could get the mpg in mixed city/highway (40/60%) driving.
FWIW, the low fuel light came on 8 miles before fill-up, at about 20 gallons used.
Anyone drive their T4R until empty to find out how close to 23 gallons the useable fill is?
FWIW, the low fuel light came on 8 miles before fill-up, at about 20 gallons used.
Anyone drive their T4R until empty to find out how close to 23 gallons the useable fill is?
I've noticed the same thing as well. I have wondered if the difference is not due to the fuel used during the start and shutdown cycle which might not be accounted for by the computer? I've been planning on checking the difference next time I take a long uninterrupted trip on a full tank of gas.
Yep... my computer is about 10% high as well.
My theory is that it's using the fuel gauge to figure out how much fuel has been used (as opposed to the actual fuel injection data), and it doesn't know how to handle the "extra" gas above the Full mark. I think the fact that filling the tank all the way, which pins the needle slightly above "F", throws off its calculation. That's making it think you used less gas than you really did.
My theory is that it's using the fuel gauge to figure out how much fuel has been used (as opposed to the actual fuel injection data), and it doesn't know how to handle the "extra" gas above the Full mark. I think the fact that filling the tank all the way, which pins the needle slightly above "F", throws off its calculation. That's making it think you used less gas than you really did.
Light_Mania said:
When is the low fuel light suppoed to come on? I couldn't find a figure in the manual so I assume it's based on the range calculation rather than a specific number of gallons.
I'm just as curious if anyone's ever pumped close to 23 gallons into their tank. In all the cars I've owned, I have run them down to vapors and still not got anywhere near the alleged capacity into the tank at the next fill up.
TeryT
New member
The computer over-reports about 7%, and the odemeter under-reports about 3%. Combined for nearly 10% off.
This has been repeatedly checked with highway mileage markers & GPS.
(While it is about 2 MPG off at the high end, when towing around 10 MPG it's only off about 1 MPG. But that's some high level math.)
Speedometer is right on though!
This has been repeatedly checked with highway mileage markers & GPS.
(While it is about 2 MPG off at the high end, when towing around 10 MPG it's only off about 1 MPG. But that's some high level math.)
Speedometer is right on though!
teotwaki
Senior Member
I recently installed slightly larger tires. Now the speedometer is slightly low but the fuel computer is more realistic.
With a heavily loaded truck, roof basket and lots of gear I calculated 18.5 MPG over roughly 1400 miles including the Utah off-roading. Highway speeds varied from 60 to 75 MPH. Off road I left it in 4WD high most of the time and dropped to low and locked for the difficult stuff.
Unloaded and no roof basket I get 20 to 21 MPG averaging 65-70 MPH on long drives. I don't let the cruise control over-accelerate on any uphill portions. I take over and keep the RPMs reasonable.
Around town about 18 to 19 MPG if I obey the speed limits and avoid leadfooting it.
With a heavily loaded truck, roof basket and lots of gear I calculated 18.5 MPG over roughly 1400 miles including the Utah off-roading. Highway speeds varied from 60 to 75 MPH. Off road I left it in 4WD high most of the time and dropped to low and locked for the difficult stuff.
Unloaded and no roof basket I get 20 to 21 MPG averaging 65-70 MPH on long drives. I don't let the cruise control over-accelerate on any uphill portions. I take over and keep the RPMs reasonable.
Around town about 18 to 19 MPG if I obey the speed limits and avoid leadfooting it.
The combined error (odometer and fuel gauge) is about 10%:
At 18mpg shown on the computer, actual is about 1.8 mpg lower.
At 10mpg shown on the computer, actual is about 1.0 mpg lower.
I have had similar results in my 2005 Limited 4x4 v8 over the past year.
edit: My calculated mileage has ranged between 15 mpg and 19 mpg. Calculated mileage has pretty consistently been 10% less than the mileage shown on the computer for each tank of gas (this is what I meant by similar percentage results).
At 18mpg shown on the computer, actual is about 1.8 mpg lower.
At 10mpg shown on the computer, actual is about 1.0 mpg lower.
I have had similar results in my 2005 Limited 4x4 v8 over the past year.
edit: My calculated mileage has ranged between 15 mpg and 19 mpg. Calculated mileage has pretty consistently been 10% less than the mileage shown on the computer for each tank of gas (this is what I meant by similar percentage results).
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V8Limited4wd
New member
10mpg?!! you must have a really heavy foot there.
4slomo said:
