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TundraGeneral discussion forum for the 2007 and later Toyota Tundra.
This is a discussion thread titled "Accuracy of average MPG display", within the Tundra forum, part of the Truck Forums category.
I was hesitant to believe the average MPG display on the Tundra, so I've been keeping track of the amount of fuel I use and the calculated mileage over the last 1800 or so miles. What I've found is that my hand-calculated average is 17.27mpg, and the Tundra's indicated average is 17.24!
Over the 8 or so fill-ups I did, the per-tank average discrepancy was up to 0.6mpg between my calculations and what the Tundra indicated, but it evens out over time as you can see. I wouldn't be surprised if the Tundra actually did a better job metering the fuel flow than measuring dispensed gasoline, as each pump might **** off differently, thus affecting my hand calculations.
I only included fill-ups where I did "average" driving - commuting to work and running around town, and omitted fill-ups where I was towing. Filling up at the pump, I always used the auto-shutoff, then depressed the handle fully one more time for the auto-shutoff.
Overall, this I'm pretty impressed. I'll keep tabs on the mileage for a few more fill-ups and will update this thread if something changes.
I was surprised by the accuracy too. Since day one I have kept track of gas purchases and hand calculated my mileage. The computer has never been off my number by more than 0.1 mpg in any given month.
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2007 Toyota Tundra CrewMax SR5 5.7L w/ TRD Package, Blue Streak Metallic/Graphite, FormulaOne Pinnacle Ceramic Tint (15%), auto-dimming mirror, Line-X Bedliner (under the rail), RS3200 alarm/GBS/hood switch, brushed stainless steel running boards, bed extender, door sill protectors, TRD rear sway bar.
ill go by the display jsut to know what it is...im not going to bother with hand calculating it or keeping logbook style entries or anything....for my purposes, it doesnt really matter. i have this truck. i drive this truck. if this truck needs gas i put some in. doesnt matter what the actual MPGs are over the life of the truck IMO as long as i need to drive it i'll feed it what it needs.....
ill go by the display jsut to know what it is...im not going to bother with hand calculating it or keeping logbook style entries or anything....for my purposes, it doesnt really matter. i have this truck. i drive this truck. if this truck needs gas i put some in. doesnt matter what the actual MPGs are over the life of the truck IMO as long as i need to drive it i'll feed it what it needs.....
But then again, you're not an anal-retentive engineer like I am.
I hand calculate to keep it honest every once in a while, but lately I haven't felt the need to. It is usually within .10-.15MPG of true fuel consumption as measured by hand. I see this as well within any kind of standard deviation that could be attributed to fuel pumping variations such as fuel temp, and the amount of fuel added until the automatic cut off.
But then again, you're not an anal-retentive engineer like I am.
haha true but ive been told i am anal retentive about other things so i guess we are even. heck i dont even look at the dollar amount when i pump gas...all i know is it needs it so i put it in...then the wife tries to balance the bank acount and i have no idea and then get in trouble haha
If I do exclusive in-town driving, the computer seems to calculate the mileage lower then my hand calculations by 1-2 mpg. When pulling our camper or driving exclusive highway or a mix of in-town/highway, it is very accurate.
It must be my lead foot or otherwise I haven't even seen 15mpg...even on a 120 mmile hwy trip! Maybe its the mods...and my stereo under the hood!
Yeah - I drive very gently. Trying to get the average mpg as high as I can get it is almost like a game for me. On the interstate, I've gotten almost 20mpg once.
I went to the beach at the beginning of the summer and followed the garmin down all the back roads at 55-60mph I got 21mpg. I recently went watuaga lake in Tennessee and got 17.5mpg and this was up through the mountains. I also am pretty heavy footed. My typical around town to and from work average is 15mpg. I have also done many calculations and found that the average mpg is almost dead on. The only thing that isn't is the gas gauge when it says empty I've went as far as 80 miles past when the low fuel light came on.
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2007 Tundra dc sr5 5.7 trd, bluestreak
Mods K&N 77 series intake, trd shifter, trd oil cap,trd pedals, under seat storage x-sp style steps, timbren suspension
2004 mercedes c230
1995 chevy beretta
1992 eagle talon tsi awd modded
The fuel economy's accuracy is due to the fact that it is interlinked with the engine control unit which measures actual fuel injected into the engine, and the distance driven via the odometer. It is actually more accurate than your "hand calculation" . . . so it goes.
__________________ Radiant Red 2007 Double Cab Limited w/Graphite Leather Interior
Factory Nav, Sonar, and 10 spkr 440W JBL stereo with Sirius (sweet) Cold Weather Pkg and Block Htr. Brushed SS Stepboards,
Upgraded Tires: BFG A/T KO LT265 65 R 18,
Curt Front Receiver, with Warn 8000lb winch back/front mountable, Diamondback Tonneau Cover.
Tekonsha Prodigy Brake Controller
DSP 16,000 lb 5th wheel hitch
Firestone Ride Rite 2445 Air Bags
Accuracy of average MPG display
Radiant Red 
Linear Mode
