I know this is the worst possible truck to compare gas mileage with a Honda Civic, But as I get used to the truck and it breaks in, I have noticed a few things... leaving in 2nd gear and shifing into 3rd at 1500, shifting into 4th at 2000, and 5th at 2500 and 6 at 2000 Rpm seems to give me the best mileage acording to the on board coumputer..

If I take the rpms higher, thiers all kinds of power, but the mileage is right out the window...

I have a had a low of 12mpg and a high of 17 mpg, 6th gear at 55mph gives the best results on the high way, I drive up and down a lot of hills, on my way home, thiers a lot of free gravity and freeway full of red lights, I coast a lot in N when I know the light will stay red...

If I have the srw open on the high way, mileage drops, when closed mileage go's up, Truck has seen quick bursts to 80 mph, I will change out the ex system for duals, only because I like the sound and I will be adding a topper...

I'm going to research every thing I can do to get more mileage out of this truck, Just to see what I can do, The Ram is not that far off the mark set by 04 F-150 5.4 with mileage...

I have the cab marker lights and regular 6x9 mirror's, no running boards... I would like to add chrome nerf bars wheel to wheel
for looks....

any thoughts and how to improve my mileage?.

And yes, I know it's a truck and I bought the Ram because I need a truck, I'm not complaining with the mileage, But extra miles to the tank is free money...

 

Yup,
Sounds like my truck. I have seen as high as 19+mpg on mine straight flat highway.

 

Your experiments on shifting have led you to the correct result:
you want to keep the piston speeds on your 3.58 inch stroke engine below 1200 feet per minute by shifting before 2200 rpm.

Here's a very long post on ways to improve MPG on Ram trucks:

https://dodgeforum.com/m_447500/tm.htm

 

Out of curiosity, what gears are you running?

I've got the 3.73 (i think) gears and I average about 10mpg.

 

That sounds like pretty good MPG, especially for a 2500 4x4. I don’t know how many miles you have on the truck, but it will get better over time. I have 40K on my truck an my average mpg since purchase is 14.7, but It's improving every year. That’s about 80% highway and 20 city. I reset my trip odometer every fill-up, and if I have my PDA with me I log the miles/gallons.

2004 I logged 364 gallons in 5147 miles = 14.1 mpg
2005 I logged 952 gallons in 14060 miles = 14.8 mpg
So far this year I’ve logged 315 gallons in 4811 miles = 15.2 mpg

My driving habits haven’t changed and I haven’t done anything to the truck that would change the mileage, so I assume the overtime improvement is from breakin. By the time I get it paid off I should be averaging about 40 mpg. By the way, my overhead almost always reads exactly 4/10s higher.

 

rear diff is a 373 ltd slip....had the truck for two weeks, and went threw my first tank off gas, I'm using my leased 04 F-150 for work, 5.4 automatic 355 Ltd slip, I never considerd the F-150 to be that bad on gas, I hate automatic's, relabilty with may last two F-150's 02 and 04 have been worse than horiable, and In general I'm not happy with Ford ( you can't get a V/8 with a stick in a F-150 ) I'm over my Km with the Ford, lease is up in september, at 8 cents a klick, I have to fix or get fixed over two grand in body damage with the Ford..

I just don't want to take my dodge to the Job site until I work proff it a 1000 times.. So I will pay to Run the Ford and save a dodge...