Hi,
I'm new. Been searching for some help on fuel mileage. After an hour of searching and really not finding the answer I'm looking for, thought I'd finally sign up and ask directly.
I've got a 2006 Mega Cab with a 5.7L Hemi automatic. It's a 4x4. Got 103,000 miles on it. 20,000 miles on a full tune up with plugs, wires, etc etc.
I'm getting about 10. I love the truck, can't afford to drive it. I'm very easy on the throttle. I do alot of highway driving. Last week, I spend $24 on ebay and bought a Fuelmaxx chip, and so far haven't noticed any difference. If I could get 4mpg more on average ( I do alot of highway), I'd spend up to $1000 to get it. But frankly, I would like to spend maybe a few hundred to get 3-4mpg. I do NOT need a programmer for torque, off road, high horsepower, etc., I just need one (or a combination of things) to get me another 3-4mpg on my daily driving.
Please help. I'd like some easy, direct answers. I feel like I've read a thousand pages on the subject and still don't really feel 100% confidant that I know what to do. I can't afford to waste money, so I need to buy what I need ONCE, and that's it.
Again, thank you, and I appreciate the help.

 

Welcome to the site. 10 MPG is not so bad as I average about 14 in my Durango, but I will move this thread to the third generation Ram section,
FF

 

i think it would be harder for u to gain fuel millage due to the size of your truck with the 5.7

 

Sadly, it ain't happening. That's too heavy of a truck for any decent fuel economy. You are probably running right about average, maybe 1-2 mpg under some of the better reported fuel economy numbers I've heard from gasser Mega owners (the ones I tend to believe, anyway).

The Fuelmaxx is a joke, just like all the other "chips" that give better fuel economy and crazy power gains:

http://reviews.ebay.com/Fake-Modific...00000001478993

A programmer may net you 1-2 mpg's but they are geared for performance gains. I love mine, but if I was solely looking for fuel economy from one, I wouldn't own it.

IMO the truck shouldn't be offered in a gas version, but what do I know?

If it was city mileage you were looking for, re-gearing from the 3.73s you probably have now to 4.10s or even 4.56s would gain you maybe 2 mpg, but you'd lose that much on the highway. Besides, re-gearing your 4x4 would be more like a $2000 modification.

Going to an e-fan would get you 1-2 mpg easy, but I wouldn't recommend it in such a heavy truck, you need the parasitic clutch fan IMO.

Keep it tuned up and check tire inflation is about the best I got for you.

These MPG threads are gonna take over truck forums, as I've heard the national average for 87 octane gas is expected to be $4.00 a gallon by Memorial Day and possibly $5.00 by 4th of July...

 

Slow down on the highway. When gas was $4.00 two years ago, I managed to get just under 20mpg in my quad cab hemi with about 1/4 city 3/4 highway driving. There is a sweet spot when accelerating that I'm not sure I can describe. You want to take it easy, but you can make gas mileage worse again buy accelerating too slow. I remember that I watched the tach, and when taking off from a stoplight I would try to keep it under 2K rpms. I would anticipate lights and start coasting long before most people. I live in a newer neighborhood where the blocks are twice as long as older neighborhoods, and if you accelerate easy, and keep the speed to around 42-43 (45 zone) I would only need to stop at the 1st light, if any before hitting the freeway. On the freeway in a 65 zone, I kept it at about 58mph. I did not use cruse control, but steadied my foot so that I was doing about 58 on the flats, but would slow down going the slight inclines and speed up a little going down hill.

When stuck in traffic on the freeway, I would steady my foot on the gas once again to try to find a speed that I did not have to touch the brakes. A times I would have multiple car lengths of space in front of me, and others I would coast all the way up the bumper of the car in front of me. If I could get behind a semi, I would do it, as they have a similar driving technique in traffic, and most cars try to not get behind them, so I could just hang back there and not have people jumping in front of me and messing up the technique.

Keep a clean air filter. Pull the throttle body and clean it every 50K miles or so (see the DIY section I believe for instructions) Keep tires inflated to recommended, and even a few psi more. Synthetic fluids everywhere. Not sure about the AC vs windows down argument if you save much gas, but I try to do windows down to around 50mph, then roll them up.

Keep the tailgate up. Unless you have an antique truck with smooth bed sides and floor, you loose mpg with the tailgate down. A group of us did this experiment with scale models in a water weir for a fluid dynamics class, and the data I saw shows the tailgate up is better. We calculated about a 5% decrease in fuel economy due to aerodynamic drag. If your getting 20mpg, that 5% equates to anther 1 mpg gain (or loss depending on where the gate is).

You might want to try the e-fan if you can piece it together pretty cheap. If it doesn't keep the temps under control, you can always sell the parts and possibly break even.

 

what size tires and rims are on your truck ? running some 20z will hurt some gas mileage , i have a 5.7 hemi also and really wish i had a diesel , my buddy has a 3500 quad cab diesel and gets better gas mileage than i do on the highway , from 70mph to 80mph i see my gauge say an average of 2 mpg differance , just like ramjam said slow down a little and maybe try and set the crusie in that sweet spot . good luck but were in the group of heavy trucks and bad gas mileage with high gas prices !!

 

i had a megacab hemi 4x4 for five weeks. luckily i work at a dealership and can buy for a little over what they give for them. i traded it back for what i paid for it when a cummins 07 megacab 4x4 came in.
i agree with the moderator guy that they shouldnt even make it in a hemi. i got about what you got with stock 33 inch tires on 20 inch wheels, a little under 10 mpg average all around driving. my cummins has 5 inches of lift and 37 inch tires and still gets 20 on the highway and 17 all around.
im a mechanic and there aint much you can do to improve the numbers, granny driving and keeping it tuned up are the best bet. any modifications you'd do to improve mileage enough to make a difference would run you more money than you could make up with the 3 or 4 miles per gallon youd get.

 

Thanks for all that input.
I will get the tire info tomorrow.

I'm highly considering selling the 5.7 and getting the same truck with a Cummins. The only reason I didn't before is that I couldn't afford the desiel version. I might be able to now, but on ebay they still get stupid money for 100K+ mile 06-07 Mega Cabs.

It always seems to boil down to money for me.....

 

Narrow freeway rib tires, no all terrains or mud tires, high tire pressures, light wheels, drop your speeds, keep your fluids and filters clean, run lighter weight synthetic oils, get a tonneau cover, remove extra weight, lower your truck...

or get a better commuter.

 

Maybe you can orgainize a carpool with someone who has to make the same highway trip and take turns riding with them in a higher mileage vehicle. I ride with my brother on our commute half the week and his car's fuel economy helps a lot. Another thing I do is try and run several errands in the same area at the same time to make the most of your trip, rather than making lots of trips for single reasons. If you can save enough by doing it, get a cheap old car with good fuel econ for your highway driving. best of luck