THE ONLY MOD you can do that WILL pay for itself in fuel saving are dual e-fans. It is the only mod I have ever gained mileage out of.

Went from 13.2 Hwy to 14.8 hwy overnight due to e-fan install + 180 tstat + coolant flush


Yeah and that is in a 97 2500 HD 4X4

 

Seriously your doing pretty good my hemi gets around 14 mpg with cat back duals, homemade CAI, and a powerwire with stock size tires... dont complain too much

 

I am getting about 14mpg with resonator delete and homemade cai. I drive about 20 miles a day, half of them highway miles.

 

No offense, but if you believe ANY one mod will net you 4+ mpg then someone has been lying to you.

 

Lay off the gas pedal. Seriously. It is the single biggest way you can increase mileage. Accelerate slowly, decelerate early and anticipate stop lights and stop signs. Limit your top speed to 55 or 60.

The second biggest way is to lay off the brake pedal. The less you use the brake, the more gas you will save, so drive accordingly.
Braking wastes gas buy turning the forward motion you generated by burning the gas into useless heat in the brakes.

Also change your air filter, spark plugs, plug wires (if equipped), and oil. Keep the tires inflated, even a little above the normal pressure (still below max printed on tire). Use the lightest oil the owner's manual allows for your engine. Take all the extra crap out of your truck, every pound matters. That will all help mileage, but again, not as much as laying off the go pedal.

 

4. Always drive downhill

 

Eeewwwww! Where's the fun in that?

 

But it says so - right on the box! Don't forget the extra 75 whp, too.

 

Best way to increase your MPG is to draft behind big trucks everywhere you go.

Wait in your driveway until a big truck goes by and follow it wherever it goes. Hopefully, its going where you want to go.

I bet you could hit 25mpg if you followed trucks around everywhere...staying within 10 feet of its rear end.


Or..do what they did on mythbusters. Coat your entire truck in clay ( I think they used clay) and cut out divots like a golf ball. They proved it majorly increased your MPG even though you add a lot of weight.

Those are my 2 cents.

 

^^^^^^^

They also did that show on Mythbusters that really showed no gain from following on big truck other than literally being on his bumper physically which is dangerous