Mileage

Mileage will also depend on what tires/wheels and gearing.

My previous 2011 F250 crew cab with 8' bed, 20" wheels and 3:55 gears would get about 17 mpg empty on the highway at 73mph 11 towing at 65mph.

Current F350 drw crew cab with 4:30 gears and 17" wheels gets 14.9mpg @ 70mph empty and 12mpg towing @ 65mph

Break-in mileage is NOT a myth. I've experienced it personally with two different brand new trucks spanning 13 model years.

The current truck had a sudden jump in fuel economy at 500, and again at 5000 miles. Probably a computer thing.

TexasChaps wrote:

Lynnmor wrote:
Mileage won't change due to break in, that's an old wives tale.

I would disagree with that statement...

In early 2000 I bought a VW jetta TDI for commuting.
Off the lot it would return about 35-37 mpg with 90% freeway driving.
I logged the mpg over the next 14 months and the mpg steadily increased until it reached 50.1 mpg average.. Mpg got better as the engine broke in, my driving habit ( speed and miles driven ) was consistent. Even more surprising was the mpg after 300,000 miles.. still averaging 45 to 48.. !!

So.. how do you explain the increase in mpg over time if not from
reduced frictional losses as the engine's surfaces "smooth out". ?

No kidding my 98 12V RAM's mileage kept improving up to 150K.

Even the hand calculated one is not perfect either, how full did I fill it? I find over the years there isn't enough difference the hand calculated one and my over head computer. Mileage is going to very from fill up to fill up because of all the veryables. So what if there is a .3 or .2 difference. I have a 50 gallon aux tank and 38 gallon OEM tank that gives me an advertised total of 88, but you can get more fuel in than what it says how much I have no idea but only a guess. I can put 4 more gal in the OEM tank after the nozzle clicks off at least 10 gal in the aux tank. A .3 or .2 error isn't going to mean squat to me when the fuel gauge get near 1/4 I start looking. By experience I know I can go 200 or so more miles. I get between 8 and 11 mpg. The wind is the biggest factor. When I figure my fuel stops I fig it at 10 mpg works well for me for the last 15 yrs

Lynnmor wrote:
Mileage won't change due to break in, that's an old wives tale.

I would disagree with that statement...

In early 2000 I bought a VW jetta TDI for commuting.
Off the lot it would return about 35-37 mpg with 90% freeway driving.
I logged the mpg over the next 14 months and the mpg steadily increased until it reached 50.1 mpg average.. Mpg got better as the engine broke in, my driving habit ( speed and miles driven ) was consistent. Even more surprising was the mpg after 300,000 miles.. still averaging 45 to 48.. !!

So.. how do you explain the increase in mpg over time if not from
reduced frictional losses as the engine's surfaces "smooth out". ?

City Driving: 16.4 - 17.1 mpg
Hwy Driving: 18-20 mpg

Hwy driving is really dependent on wind speed. If my truck regens on a trip it will drop .5 mpg.

deltabravo wrote:


Yes, that is correct, which is why my hand calculated varies from the the computer mileage; meaning my hand calculated mileage difference from the computer mileage is because the tank is never filled to the exact same amount each and every time a fill up. This is due to the fact that there are so many variables involved, it's pretty difficult to fill it to the same level each time (unless you had a sight glass on the tank).
This is what I was trying to convey in my original message, but my wording may not have been the best.

I did realize, after I posted, that I only talked about one side of the equation.

If one were to calculate after a number of fill ups, the error could be reduced to an insignificant number. For example if the error was as much as 1 gallon per any one fill up, the error would still be only 1 gallon after 10 fill ups.

I just posted the question to see what others were getting with their trucks knowing that driving methods differ from one driver to another ,nothing more than a interest of information.

I'm not a mileage nut if I were I wouldn't have bought the truck, my Sunday driver 1967 SS Chevelle gets 8 MPG if I keep my foot out of it and that's tough to do what have the HO if your not going to let them run.

I like to keep up with the mileage for a number of reasons. One of the most important is to make sure the rig is operating normally. If my mpgs were to drop noticeably, I'd be looking for such things as a brake caliper hanging up, an injector going bad, the tranny slipping, etc and etc.

I also like to know how headwinds affect my mileage, and my speed, and the hills, and the etc and etc.

Lynnmor wrote:

deltabravo wrote:
They display is always slightly different than the hand calculated, some of which can be attributed to a slightly different level of "how full did I get the tank this time compared to last time." There's too many variables involved to get a fuel tank filled to the exact same level each and every time.

The display does not use the fuel level in the tank to calculate mileage, it reports the amount of fuel injected in the miles since last reset. The variations are caused by less than perfect injection systems and odometers. There is always a tolerance, nothing is perfect.

Yes, that is correct, which is why my hand calculated varies from the the computer mileage; meaning my hand calculated mileage difference from the computer mileage is because the tank is never filled to the exact same amount each and every time a fill up. This is due to the fact that there are so many variables involved, it's pretty difficult to fill it to the same level each time (unless you had a sight glass on the tank).
This is what I was trying to convey in my original message, but my wording may not have been the best.


All these "what MPG will this or that HD truck get" are kind of comical in a way, and I don't mean this as any disrespect towards anyone, but a tow vehicle is meant to do work. Mileage "is what it is..."

If someone is so concerned about getting a few miles per gallon better, and are planning on a budgeted amount of fuel costs based on X mile per gallon, they probably should not be an RV'er. LOL.
Or spend less money on foo-foo coffee drinks at the Latte' stand and save that for fuel.