I know this is really obvious, but I thought I'd share my experience.

2 tanks ago I had 240lbs of quickrete tube sand in the back with about half the bed filled with snow. The roads were plowed/sanded by now, and I didn't really need them, but I never took the time to shovel it out.

The first tank was getting ~10mpg (60/40 city/highway).

I drove the next tank as lightly/slowly as I possibly could, and still got ~11.8mpg (60/40 city/highway).

I shoveled all that snow out, removed the sandbags and went on a little trip to pickup the roll bar. This time I got 17.2 miles to the gallon (all highway).

Yes, I know highway driving gets better gas mileage, but I also credit a 7mpg jump from a lack of weight...

So whoever got hit w' the storm, shovel that bed clean!

 

what kind of trips were the ones that got you 10mpg? im getting 12 right now because i dont go further then 5 miles so my engine is never at running temp which is makeing me run real rich...

if your first 2 tests are all short then the long road trip to get the bar gave you 17, it could just be that you ran it at a good temp the whole time...

 

yeah i doubt the snow made that big of a difference. i still get 14 with a load of wood in the truck

 

might explain my crappy mileage.. but its not so much snow and weight from stuff getting into the bed, its from my box.. about 200 pounds of tools and chain in a 25 pound box..that can add some weight

 

the first year i had my truck i had about 300lbs of sand in the bed (6 bags) then the next year, im like screw that. while the wieght made a smoother ride, the gas mileage was in the toilet. and i didnt notice THAT big os a diff with traction

 

240lbs is a lot you shouldnt need that much

somewhere around 100-150 should be plenty!!

with 4wd i dont run any weight.

 

my gas mileage jumped from 22 to 26 just by keeping my foot out of the gas the whole time, and thats city and highway combined, just like previous tanks.