12.5 MPG on the Interstate...What is going on?

[LSUMatt1514]

I've been watching this very closely since purchasing. Around town, it is down around 12.0 but one day I did drive it about 150 miles roundtrip from Birmingham to Montgomery. Cruise was set on 75 mph the whole way. I watched it like a hawk and the highest it got was 12.5 or 12.6 and the distance to empty did reflect what I was seeing from the computer (not to mention the gas needle steadily moving toward E). Is this legit? I know I am losing around 1 mpg having a 4x4 and the 20" wheels don't help, but 12.5 mpg is a FAR cry from the 17 Hwy that the truck was rated for.

Air filter isn't clogged and I'm using 89 octane mid grade BP or Shell gas.

Give me some tips guys...this is really, really low...or is it normal?

Thanks!

Matt

[seadragon]

Did you reset the MPG computer before your trip? If not, it may not change much since it will be showing you the average MPG for all the miles logged since the last reset. Also, try setting it to instant MPG readout. That will show you what MPG your getting at that exact moment.

75 MPH is a little on the fast side for good mileage though. I cruise at about 65 and I get 19 to 20 MPG consistently on the highway. Once I start driving around town though, it drops to about 14. My average is about 16 MPG.

One more question... did this low MPG just start happening recently? Have you driven the same stretch in the past with good mileage?

[FIVEPOINTSEVEN]

I've found optimal mpg right around 70. Also yes I recommend resetting the ECU also and keeping the truck in 6th gear as much as possible. If you are constantly dipping into the throttle that will explain 12.5mpg.

[s_srobertson]

What do you have in the back?

[FIVEPOINTSEVEN]

I easily average 16.5mpg on my 250 mile trip home with the BFG's. Rock you gotta remember you have RH, BFG's, and 4x4. I don't have any of that stuff which causes resistance. Its funny how little things can affect your mpg...I think just losing my light bar with lights picked up .5-1 mpg on those long trips just from wind resistance.

[MMichaelJJ]

With my 35 Toyo M/Ts I average about 10. You have to remember, you're asking guys what they get driving in THEIR area. For me, if there is ANY type of grade, I'll drop down to low double / high single digits. If I'm cruising on FLAT road at whatever speed with the RPM around 1500ish, I average 15.

With that said, that does seem low for a stock Tundra. But look at the bright side, you're getting better MPG than me.

[FIVEPOINTSEVEN]

I stay anywhere from 65-75mph and rarely creep up above that. Unless somebody wants to mess around which never happens lol.

[Someguy123]

12.5 sounds about right for an average MPG. this truck drinks fuel like a bastard. but to check your MPG, you should try resetting your trip odo. everytime you re-fuel. then you can compare how many gallons you re-fuel, with how many miles you travelled. and you will have a better calculation.

but i generally drive about 85. and i dont think i get better than 13mpg.

[FIVEPOINTSEVEN]

I see 19 and 20 on the instant mpg readout...Not average though.

[LSUMatt1514]

Well...I just don't get to drive the truck a whole lot because I've got a little Infiniti G20 that I commute to and from work in daily (110 miles round trip). I am NOT running up the miles on my new Tundra nor getting tattered with rocks and debris from coal trucks daily!

I have not reset the computer or the information center. I'm assuming you guys just mean by "resetting" to disconnect the negative battery terminal for 15 minutes or so in order for the ECU to reset and then re-learn the shift points, air/fuel ratio, etc.?

I don't drive it enough on the interstate enough yet to rountinely see what's happening. I would expect in the 13 range around town but not on the interstate. I will play around with it this weekend. Thanks for the feedback guys.

Matt

[Tsbarro]

Hey, I recall that your truck was a demo with 5k miles on it.. You should probably do a ECU reset by disconnecting the battery for 15 minutes or so. Who knows how it was driven beforehand, but its atleast something that should be done so you can rule it out.

[guntech]

Mine dropped about 1.5 mpg when I went to a more agressive tire (Goodyear Silentarmor - same size). I notice a BIG difference in MPG between 65mph and 75mph on the original tires. I haven't put enough miles on the Goodyears to play around and tell anymore.

[mxsjw]

Originally Posted by LSUMatt1514

I have not reset the computer or the information center.

There's your problem right there...

Re-set the average MPG on the multi information display on the dash.
Push the "select/reset" button till you get to the avg.
Then push and hold the "select/reset" button till it clears to 0.0 on the display.



Now, go get and the highway and prepare yourself to be pleasantly surprised. You'll start seeing numbers like this and the others above...as long as you can stay out of the stop and go stuff. Add 5% to my numbers to compensate for my larger tires.

[TundraBay]

mx is very fond of that 2nd picture of the brief moment when he was getting Prius mileage on a Tundra, while decelerating, going downhill with a tailwind!

[ballin]

winter blend gas with ethanol. always bad mileage in the winter and great mileage in the summer.