I had enough trouble with emissions on my 6.7 so am considering a 5.9 automatic truck with 3.73's.

I recorded every drop of fuel I put through my 6.7 since new - it used 1574.37 gallons in 25,634 miles which is 16.28 mpg. These are unloaded miles most of it highway cruising 60-65 mph, 60 miles per day to and from work. I've seen overhead readings above 22 and some long trips were hand calculated over 19 mpg, but it's the long haul that I want to improve on.

Have any 5.9 owners logged their fuel consumption like this? Just trying to understand the real economy numbers over the long haul.

 

I have been, but I bought my 06 used last December, so its only the last year.

So far Im about 17 avg. I think about 10000 miles. (the file is on another computer)

I actually only had three tanks below 16 mpg and if it wasn't for those my avg. would have been about 0.5 mpg higher.

Its not as good as my 01, but Im still plenty happy with it.

Have a good one.

 

I have. I have log the number of gallons since I first took her home and do all my own maintenance that is not covered under the warranty. Right now my mileage has gone down a bit due the cold snap that is blanketing the area (winter weather) right now and I show 16-17 on the over head for around town driving and 18-19 on the highway unloaded with the current weather we are having. Otherwise it is about 2-3 mpg better. When towing I run about 13-14 around town and going the the road 16-17 that is with 2.5 tons of hay or two horses out back in a trailer.

I did notice that I get the best mileage when the air temps are around 70 degrees. These averages are back by hand calculations, which is figured by miles driven divided gallons used to fill tank back up. I would list my total for gallons consume up to the last fill up, but that info is in the truck right now. My mileage is a little over 53,000 miles and I am due for an oil change.

Forgot to mention I have a 6 speed NV5600 with 3.73 and the LSD along with 4wd.
Shawn

 

I have record all of the following since new: Date fuel was purchased, odom mileage, trip mileage, # of gallons, $ per gal, total $, hand calc mpg, overhead mpg, and recently engine hrs, hrs on that particular tank, and average speed on that tank. I have 24,400 miles right now, but only have up to 22,497 inside on my computer. Over the length of 22,497 miles, I have spent $4922.28 on 1458.911 gallons of diesel for an average of 15.4 mpg. The driving is country roads with mostly 60 city/40 highway. I also have a 4.10 gear ratio as well.

 

The totals below are since I bought the truck in May '07. Total mileage now is around 82,000.

Total Miles........34,823.80
Total Gals.........2,077.71
Avg MPG...........16.76
Total Fuel Cost...$7,211.80
Cost per mile......$0.2071

Min MPG 11.52
Max MPG 19.58

Min MPG was pulling this load.

http://grangercattleco.com/haulinghay.html

 

I've got just about 10,500 miles on my truck and have done hand calculations on my fuel usage since the second tank full.

Right now my average fuel economy is 18.71 mpg.

This will get higher as time goes on I believe as many of the first tanks averaged out to about 17 mpg. My mileage has steadily improved and right now my tanks are averaging about 19.5 mpg with a couple over 20.5 mpg!

I've got a big spreadsheet where I enter everything in and it does all the calculations for me. I've got it showing just about everything I can think of plus graphs. I do that for every vehicle.

 

WOW, I am glad to see I am not the only one ANALytical about this sort of thing.
My numbers would not be of much use though, since I only have 13k miles and 4k is pulling a 27' 5th wheel where mileage is around 10mpg

 

Are you guys getting this info from the truck ECM ? I have a 01 it had 130000 on on it when I got it . I check by calculator at ever fill up around town not pulling anything I get 16.5 to 17.5 on trips around 21mpg . If you are getting your info from the ECM do you have a reader of your own like you check for codes with ?

 

What kinda info are you talking about getting from the ECM?

All my calculations are done by hand. I fill the tank to very close to the same point every time. I get it to a point in the fill neck that I can see, then get the mileage and calculate from there.

The mileage from the overhead is always in error. I do record it and enter it into my spreadsheet. My spreadsheet calculates the percent error between hand calculation and the trucks calculation.

Interestingly my overhead gets more accurate if I load the truck. The percentage of error between the hand calc and the overhead drops to about 4~5% when loaded. Running unloaded the error is usually 7~10%. Long trips also reduce the error as well.

 

I to have a log book and have logged every item added/removed from the truck. I have never entered this information into a spreadsheet to get lifetime stats. Maybe I will start entering in a spreadsheet but going back over 4 years of entries does not sound like fun..

Dave, Is your spreadsheet something worth sharing? Save me some time creating one if you have worked out the bugs...

Agree on the overhead.. I use overhead as a baseline but hand calc everytank in my paper log.