The best and least expensive way to get better gas mileage is to change your driving style. Don't be in a hurry to get up to speed, keep distance between the car in front of you so you can let off the gas and let the engine slow you down rather then hitting the brakes and find a good speed on the highways that doesn't burn up too much fuel. I found that my 02 dak with a 4.7Lt gets its best highway mileage going no more then 65 anything above that and you can watch the gauge drop. Every time you touch the brake pedal it waists fuel. Make sure to always check your tire pressure with any change in temperature, a few PSI can make a huge difference over time.

 

Links? I can't see them (it)

 

If you don't have a 3.55 rear axle ratio get that. And like Jason said treat the pedal nicely. I just drove my Dakota home on the highway, I got 22 mpg, that was even with the heavy traffic I was in, but I kept my speed at 62-63 mph. My truck is stock at the moment with only a radio mod. The biggest problem is you have a 4.7 in the truck so your urge to floor it for fun has downsides for your mpg.

 

Yeah they're always temping to floor it beat my buddies 2012 cummins with my 03 Dakota haha

 

Ya when I get all the simple mods on my truck, I will have a hard time keeping my city MPG in the double digits

 

Tires will make a huge difference. Commuting 100 miles a day taught me to be conscious of mileage. I run my tires at 40psi, and set the cruise at 55 vs 70. 8mpg difference on the same commute, and it added about 12 minutes to a 100 mile trip.

 

tire and air pressure make a big difference. and dont stomp on the gas