Originally Posted by DaveB.inVa

I consistently get right at 10% higher on the overhead. I have an excel spreadsheet for about everything in my life from my vehicles mileage, maintenance, rounds fired in my firearms and reloading data for my .45.... ect!

I do average just under 20 mpg hand calculated though with the overhead reading about 22 mpg.

There was a definite increase in my mileage when I added the Smarty, it is easily observable on graphs from my spreadsheets. Unfortunately the graph for diesel prices over time seems to rise exponentially!

Originally Posted by Dodge89W250

when you calculate it out manually your just getting a ruff average of all 30 something gallons you burn.. the over head is telling you what your getting at that exact time you look.. the mpg fluctuates do to stop and go or if you have a heavy right foot and etc..... so its not realy a scam its what your getting at that exact point you look and at what rpm and in what gear.

Originally Posted by Dodge89W250

when you calculate it out manually your just getting a ruff average of all 30 something gallons you burn.. the over head is telling you what your getting at that exact time you look.. the mpg fluctuates do to stop and go or if you have a heavy right foot and etc..... so its not realy a scam its what your getting at that exact point you look and at what rpm and in what gear.

Originally Posted by markp

I have 2006 Big Horn SLT 5.9 ctd -48RE with 14k miles

I just did a MPG check doing this: Filled my tank all the way UUPP till I saw liquid [not first click or foam]. Then put about 250 miles on the truck going back forth to work [ 10 miles] and a few sixty mile trips on the freeway at 70 mph. Also includes just a couple minutes warm up in the morning while getting my jacket; lunch box etc.. Then refilled using same method above. Now with hard numbers off odometer I'm getting 14.496011 mpg BBBBUUUTTT the mpg up on the fuel analizer thingy from Dodge says I'm getting 16.5 mpg ?? Is this a scam issue and I use the term "scam" lightly; into thinking your getting reasonable fuel mileage from one of Dodge's big fat trucks and telling all of your none Dodge lovers how good your fuel mileage is compared to their fuel hogs; or I don't know how to use the fuel thingy?? Actual 14.5 mpg is far from 16.5 mpg when your braggin; if ya know what I mean---->

Originally Posted by TreeFarm

No. It's the average mileage since the last time it was reset. You can prove this yourself. Go to the top of a long steep hill and start down. Reach up and reset the overhead. It will read a really high number, like 30 MPG, or so.

Drive for a few weeks without reseting the overhead. Now go back to the long steep hill and start down. You will find the overhead reads something much less than the high number you got right after the reset.