Dragging brake caliper? Fuel filter? O2 sensors? Ambient temprature, alignment, all sound small but let's pretend you lost .5mpg for each one listed that's 2.5mpg, some may in reality cause larger losses in fuel economy

 

Really? How far are we talking on the highway, here? Short trips on the slab to get from the country into the city, or actual cross-country trips of 100+ miles at a time? The morning beltway commute doesn't count. Just because you are technically ON the highway, doesn't necessarily constitute "highway driving". Do you have your right foot on the floor any time you are under acceleration? Cruise control at all?

I have a 2005 5.7L 4x4 QC with Pro Comp 33x12.5/17 A/T tires and 3" body lift. The only thing not stock, mechanically, was a Flowmaster 50 series SI/DO exhaust. The truck was routinely driven from Arkansas on distances to such places as Pennsylvania, upstate New York, Atlanta, Memphis, Dallas, San Antonio, New Orleans, Florida, etc. On true highway driving trips, I averaged (by hand) roughly 18 mpg, with the cruise set between 70-75 mph most of the time.

If you are only getting 12 mpg on the highway, you either have a big lift and big tires, or a big problem. Option "C" is that you are just doing it wrong.

 

Chet,
first of all, dont blow a gasket dude, the mpg numbers on my old 2005 are realistic. (city mpg was no better than 8 to 9 mpg on a good day) I see in here that some of the others that posted, aren`t much better than my old hemi was. So calm down a bit and dont be jumping on me telling me i`m doing something wrong by giving me your "OPTION C" attitude. Some of these older hemi`s were just plain pigs on gas. I owned the truck for about 8 months, and thats the reason i got rid of it, it was the absolute worst vehicle i`ve ever owned for mpg. I live in the penn state area, nothing but hills around here, so mpg DOES suffer whether you believe it or not...! I also find with your truck for what you describe, is VERY hard for me to believe what you say that you`re getting for mpg. (18mpg at 70/75 mph...?? i hardly believe that statement) The truck i have now, is a 2010 1500 4x4 QC hemi, i average 14 to 16 in the city, and 20 to 22mpg highway, and thats hand calc`d. Absolutely nothing has been done to this 2010 truck, with the exception to running valvoline synthetic motor oil in it. I will also add, i`ve been a automotive mechanic for 40yrs, (or for the newer term they use today, automotive tech) i pretty much know how to calc mpg.

 

Make sure the air filter is clean. Seems obvious, but it can easily be overlooked, and a dirty/clogged one will kill mpg performance.

 

I've seen MPG statements from guys ALL OVER THE PLACE. Although the 4.7 guys REALLY have the widest gap in numbers. From the trucks I've seen, been in, helped guys work on, etc. I find that on average a relatively unmodded 4.7 in a QC 4x4 1500 will get about 12 city and 17 Highway and a Hemi will be roughly the same, maybe even a mpg or two better. MDS doesn't make a big difference either unless the rig is a strictly highway rig which might tend to do a mpg or two better. Some guys get better and some significantly worse. Why? I dunno.

As stated, with the weight and mods on my rig, I am perfectly happy at about 13 city and 16.5 highway. My 2nd Gen (1500 5.9 RC 4x4) never saw double digit MPGs unless it was all on the open road when I might could eek out 12 mpg if I was easy on it. Mods on it were a K&N drop-in, shory headers - true dual exhaust, 3" of body lift, a level up front and 35" tires...

 

i own a 2007 dodge ram 4x4 with a 4.7. my truck never has got very good fuel mileage. around 11 or 12 mpg is it. i am looking for up grades to help power and fuel mileage. anther problem it has is going 65 to 75 mph it shifts in and out of overdrive. i had a 2004 dodge same truck with 33's and it didnt do it has much has this 07. what is the best upgrade that will help fuel mileage and the kicking out of overdrive. i am running 285/70/17 hankcock m/ts...i would love to put 35s on this truck put dang the fuel mileage and overdrive problem makes me wonder if this truck will turn the tires. i know gears will help alot put with with just 285/70/17 i shouldnt need gears. i have been searching on the net for upgrades. i think air intake and throtle body and full exhaust will help...does a chip help that much on a gas engine? and electric fan should help huh? any dodge owners with this same problem? what was the solution? email me with help please N_Downsrs@yahoo.com..i will upload some pics

 

I've had some time to take a look at a few things the Throttle body is spotless, I cleaned my KnN it was a little dirty, I'm going to check the gap on the plugs this after noon. It seems the gap in mpg between truck to truck varies a lot so Ill just keep pluging away and see if anything changes

 

No gaskets blown. I'm from PA, originally, and have spent a good deal of time up there in my truck. I know the hills quite well. Visiting my folks up there, I'd get abysmal mileage around town (well, actually, out in the rural area we lived), not to mention that you could pretty much watch your oil get darker if you checked it every day (yes, that's hyperbole). Now, I also asked what kind of highway driving you were doing, specifically, and what kind of mileage intervals are you doing your calculations at? ALL highway, or a mix, or what? Figures will be skewed if you drive around stop-and-go all day and then try and figure highway mileage after the fill-up on the way home. I can assure you my personal hand calculations are quite correct for highway mileage. However, they were calculated off of long full or near-full tank runs of interstate (both flatlands down south, and mountainous regions heading further northeast). There's going to be a discrepancy if you are trying to calculate "highway" miles when most of the tank wasn't spent over the road.

Considering that the speed limit almost everywhere south of the M-D Line is 70 mpg in most places, that's about where the cruise was set. I've found that below 2200 RPM and your gas mileage stays relatively safe. Cruising for any length of time over 2200-2300 RPM and you should bring a few extra gas cans with you. My truck is a 2005, as well, so, I guess it falls into that "older HEMI" category. Look around the site a bit and search it out. I'm not the only one who gets those kinds of numbers. Although it wasn't what I intended when originally buying the truck, it ended up turning out that probably a good 35,000 of the now 55,000 miles on the truck (it's still but a babe) have been over-the-road highway miles. Had I known that it was going to end up being such the interstate famwagon, I probably would have opted for a different vehicle. However, as such, I have confident experience in its behavior, fuel mileage-wise, after so many miles logged at speed. If you think PA is hilly and lumpy, you should try this German countryside. I think it was built uphill both ways... I haven't started logging my mileage over here yet, as I've only had the truck on-soil for about a month now and have only put gas in it three or four times, and never from near-empty. I need to get a new notebook and start keeping track of it. Even the autobahn is like city driving here, though, because you are on and off the throttle so much since nobody goes the same speed as anyone else.

Perhaps you truly were getting those types of figures you purported without a heavy right foot (or, left hand, in my case). If that's the case, then I do believe there was something wrong with your vehicle, be it something as simple as needing an oil change, tune up and good cleaning, or something much more severe. Was it an extremely high-mileage engine? Like I said, look around here and you'll see that I'm reporting about average highway numbers. Around town (everyone's town is different... mine happens to be hilly cow country with constant downshifting) is a different story, of course. I know I don't have to tell you that gas mileage correlates directly to driving style, and with a steady throttle over long distances, those kinds of numbers are quite feasible. As a 40 year "automotive tech" (I prefer "mechanic", as well), I'm sure you understand this, too.

 

E-Fan - hands down... Relatively low initial cost and it'll give a solid 2 MPG and about 14 more HP free'd up at the rear wheels.

Tuners do a good bit for performance and a side benefit might be a small mpg gain, but the consensus is the PERFORMANCE tunes and 93 octane gas does better than the so-called "MPG Tunes" which all tend to de-tune the engine requiring more throttle for the same effect, thus negating any MPG gains they may otherwise provide...

BTW fellas - I have ABSOLUTELY no problem with debates or guys giving opposite view points on a subject. Hell, plenty of people don't agree with some of my posts. BUT it's gonna be done in a respectful way on this site with no bashing, name calling, taunting, etc. OK???

 

E-fan is the next addition. Hopefully within the next month as soon as the holidays are over.

I apologize to all if anything I wrote came off too harsh. Unfortunately, context and intended inflection is hard to grasp on the flat screen. On top of that, English is not my first language. Sarcasm is my native tongue. I'll work on it, though...