14 Mack, 4.6 mpg? Can I get better mileage with it?

Mid roof pulling a reefer. Try 62 mph.


How long have you driven it? Air filters changed with fuel and oil.


The tires aren't helping.

 

I certainly hope you're getting an above average rate you're happy with to be operating under such tight deadlines and high pressure.

 

Way too many revs for your speeds. As said by others, get some tall 24.5s or regear. You need to get those down closer to 1250.

In addition, get the air dam on the roof and tighten the gap between the sleeper and trailer. Cab extensions? No? Get some ASAP. Basically set your 5th wheel as far forward as you can while still legally scaling out the steer. Less air gap = better fuel economy.

Until you are able to do that, don't accept a load that will require you to go over 60. That wet kit = set up for short hauls, not highway runs.

 

Sign on to a tanker company.


The tires I'm thinking are pretty bad. I have a mid roof. When I haul dry box, I have to stay around 62 or less to get good mileage. I changed from xdn2 michillin to yokos I lost fuel mileage. When I did tanker I got high 7s at 78k with the xdn2. Then I went to high 6s. Dry box I was low 6s.

 

mDrive comes either OD or direct. The OD has a top gear ratio of 0.78. You said 1530 @ 70. In the calculator I guessed at tire height for low pro 22.5 (40") and it's about right for an OD transmission, so that's a lucky break.

Seriously, even with the crappy chinesium tires and no roof aero, you should be in the mid 5's at least. Aside from what's already been mentioned, running the overhead and check for brake/bearing related drag. Inflate all tires to max printed on the sidewall until you get rid of them.

Tall 24.5 tires/wheels will get your rpm down to 1370 @ 70 and likely help, even more when you can slow down. Speed + that mid roof with a van trailer is subtracting 1 mpg off easy, if not more.

 

That's your problem, right there.
Not the gearing or the mid-roof.
I would slow down a little with a mid-roof, though.
Or add a deflector too.

 

Your MPG should be 7 - 7.5.
There is something wrong with the engine.

 

Ideally maybe. I rented a '16 Pinnacle a couple weeks, set up about like his, but with the tall roof fairing and running mostly right. It barely got 6 hauling a reefer at the speed limit. It was a rental, so of course had crappy recap drive tires and most likely the worst preventive maintenance ever. With some TLC and a careful driver maaaaybe it could hit 7's.

 

Something wrong with the engine fuel map in the ECM.