Mpg on peterbilt 579 Cummins x15

Asking another driver their true mpg is like asking a woman her weight.

True mpg means ifta quarterly filing..not “on my dashboard it says 12 mpg going downhill”

 

Way too many factors. I’ve seen 9.4 empty and I’ve seen 7 empty. I’ve done 7.5 at gross with tarps, flat road and plenty of time. I’ve also done 4.8 with 25k on through the mountains and running 85.

 

I know a guy with a 21 579 500 horse X15 Efficiency series, 13 speed with 3.25 rears on low pro 22.5. Standup bunk 250” WB pulls hopper and loaded to gross about 75% of all miles. He got 6.4 mpg this last quarter. 6.7-6.9 during the warmer quarters with the better fuel blends.

Specs and what you’re doing, not just the weight, have an impact. These newer fuel sipper spec trucks might get 8 or 9 mpg pulling relatively light loads in a van with the trailer #### near slammed into the sleeper and you stay below 60 mph. Same truck pulling 48k of tarped sheetrock where the load is 4 feet or more back from the front of the trailer will only get 6 and that’s if the wind is behind it.

 

2022 579. 510 Paccar with 12 spd trans and 2.79 rears. Currently at 7.37mpg lifetime on paper, tracking every tank of fuel. I have a little bigger sleeper gap than most and I see a drop in economy with winter blend fuel.

If you ask someone their mileage and they can’t give you one single number then take it with a grain of salt because they’re not really tracking their fuel tank to tank to get a weekly, 4 week, and lifetime averages. IFTA filings will get you close but they can be fudged unless you start the quarter with a full tank and end the quarter with a full tank.

 

Life time on my Volvo so far is 7.73 so far. Been going down since winter started last 30 is 7.10 and last 60 is 7.5.