I've used my SuperChips on all settings in both city and highway driving and the highest gain I saw was 1 mpg. If you're getting that much of a gain your computer is lying to you or your truck is in some need of maintenance. Or you just drive like a grandpa.

 

Tuner first, save the TB for when you have some other stuff done (the rest of the exhaust, tuning, maybe a cam) then the TB will shine. Bang for the buck (depending on whether you are 2 or 4wd) is gears. Changing those almost completely changes the nature of the vehicle (especially if you couple it with a converter change).

 

I drive to work and back thats about 6 miles and if I need to go anywhere else but it is all stop and go. I still have 1/4 of a tank to go and I am already at 210 miles on this tank. I only got 230miles on my first tank so it has for sure helped me. I am going to change my plugs soon not sure when the guy I bought the truck from changed them last. I drive normal I try not to get on it to much lol.

 

I wrote a post a long time ago about fuel savings with the e-fan: here.
Since that post, I have installed the flex-a-lite 183 e-fan, and even with a 180* thermostat, I still gained a little over 1mpg. HP gains with the e-fan have been rated between 15 & 18 RWHP.

I currently have a 3" lift, programmer, exhaust, 180* t-stat and e-fan and I get around 15mpg mixed driving. It would be even less without the e-fan, since most of those things reduce MPG while boosting HP.

I had a CAI at one point for about a year, but it was a pain to deal with, so I went back to the stock air box (2008 4.7L, very similar to the "hemi hat"). I never noticed any difference in MPG one way or the other, so I can't say I miss it.

 

There's a few cheap and weird tricks for better mpg. Keeping a truck washed and wax actually improves mpg a teency weency bit. Another one don't blast your a/c if you don't need to (I live in Texas so I gave up on this one lol). Keep tires properly inflated. A bed cover will get you 1 mpg better. Efan will help, cold air intake won't help unless its a REAL cold air intake, which aren't the ones you buy for under $500. Exhaust with more flow (NOT FLOWMASTER) will help some. A tuner might help a tad, but you're going to spend more money than you'd save on gas.

 

I'm pretty skeptical of 15-18 rwhp, oh and btw would it void your warranty?

 

you dont have to sacrifice one for the other, i find that to be bullsnot....im running a tuner and im getting better HP and MPG at the same time, with the fact that i have a CAI and Dual Exhuast, now i know when i get my efan in its going to get better, but back to the topic, Hemi, i would say get all three mods, and if you dont already are you plannin on putting a CAI and Dual Exhuast

 

An E-fan does produce about 15 rwhp. It eliminates the parasitic loss of power that the clutch fan takes away since it's driven by the engine while an e-fan isn't. There's a reason why next to gears it's one of the best mods you can do for the money

 

Update you were right about the overhead display it was lying to me. I got 275 miles on a tank so a got 11mpg thats still better than the 9.2 mpg I got before the tuner.

 

08....15-18 rwhp would be noticeable in the seat of your pants, and when I did my Flex-a-lite 180 years ago, was expecting just that, but felt absolutely nothing at all. I'm sure they're good for a few extra hp, but not what is advertised. The best bang for your buck performance mod is gears, always has been, always will be, and actually can achieve a mpg improvement at the same time, if your vehicle was geared wrong for conditions it faces ie oversize tires