I can't count how many different threads I've read on different ways to increase MPG, and the different things I've tried. In theory, I should be getting around 30mpg, but that hasn't happened. So hear is a list of things that I've tried throughout the years including different pumps, additives, tires, speeds, etc. and the last 10,000 or so miles and the results (everything has been hand calculated)

My truck started stock with an Edge EZ and 4" dynomax exhaust from the resonator back. Truck is listed below.

Driving styles:

I keep reading all these threads on how driving slower adds 2-3 mpg. I have driven steady anywhere from 55mph up to 70mph. I will admit, above 65mph with a 4:10 rearend my average drops about 1mpg, but between 55 and 65 the difference is around .5mpg. As far as acceleration styles, the only time I saw a real difference was practially flooring it everywhere. THAT dropped my average by about 1.5. However driving "normally" vs "like there is an egg under the accelerator" makes a difference of less than 1mpg. I'm not doubting anyone elses claims, these are just my results.

Fuel:

Never saw a huge difference between winter and summer blend. I average about 16.5 in the winter and 18 in the summer. You might say that it is the fuel right? Wrong I think. It is the outside temperature that makes the difference for me. I get a better average when the temp is warmer on the same fuel than when it is cold. I know that is common sense, but the different blends never make a difference for me. An interesting note however, I as well as a few friends have noticed a difference between stations that we use. As much as 2mpg! I try to stay with the same stations as much as possible.

Additives:

I used power service for years, in my '89 and my '02. I never saw a difference between using it and not. Almost seemed like a waste of money as this point other than the anti-gelling properties. I have sinced switched to 2-stroke oil. At best I think I have gained .5, but there are too many variables to be certain. The engine definately runs smoother and after reading pages on the pluses and minuses of different additives, it seems to be working the best for me. Also, it has been -10*F at my house, and the truck has sat for a week in cold weather with no gelling issues.

Cold air intake:

Went from stock to an AEM dryflow replacement filter added to the end of the stock tube. I also made my own heat shield. Difference from stock...none.

Exhaust:

I just recently went to a full 4" from the downpipe to 6" mitre cuts. At best I have seen around a 25* drop in EGT's at cruise. No better fuel mileage and no 200-300* drop. I did notice a nice little punch in the midrange though. An interesting point on something I tried that made the bigest difference of anything I've tried...2 mufflers. I tried putting 2 straight thru mufflers back to back to keep the stacks quieter. I lost about 1.5mpg and my EGT's went up by 100* at cruise running that way. The truck seemed sluggish and I was consistently over 10lbs of boost even at cruise when I am normally around 7lbs. I took off one of the mufflers and oddly enough the stacks got quieter! I lost the ultra-low tone that was the result of too much muffling (is that a word?) I got my fuel mileage back and everything seems to be back to normal. Moral of this story, don't run 2 mufflers!

Toneau cover:

Ran with and without for 1000's of miles. No noticeable difference at all.

Tires:

Ran with 235/85r16 Wildcountry XRT II Highway treads with about 50% tread. I ran those at 80psi all around. Wore the centers out quicker than the rest of the tire. New tires are Toyo A/T 235/85r16. Run 65psi in the front and 50psi in the rears (unloaded) and there has been no noticeable difference in MPG. I was worried at first, but nice to see I can save my treads!

Injection pumps:

Tried the II HRVP, didn't like my electronics, so I went back to a stock pump. Nice power difference with the HR, but no difference in MPG.

In writing this, I hope I didn't mean to offend anyone and their claims, these are just mine. After years of trying to gain that elusive MPG, I have come to the simple realization that I have a great truck that gets 17-18mpg all day long unloaded, 14-16 towing 5000-10,000lbs, and miles and miles of ear to ear smiles

 

OK, I'll weigh in here.
I'm one of the new guys here and trying to soak up lots of useful info to decide what CTD truck fits me best. MPG is one of the priorities as I currently have a Hemi QC 1500 gasser that gets horrible mileage as I am certain they all do.

It looks like you have a 3500 dually with 4:10's for which I would think 17-18 is excellent MPG. Thats a BIG truck (my 1500 gets 11-12, not towing). BTW, I've heard most have seen MPG drop slightly with the new ULSD also. I don't keep good enough data on my tractors to notice a difference yet there.

Anyway, after reading lots of threads on truck MPG on several web forums I've come to a few conclusions myself. The number one of these is you "play the hand you're dealt". What I mean by that is, I now think MPG for a population of trucks (all with the same basic engine - diesel or gas) is going to be determined mainly by a few fixed and a few variable factors. The fixed are:
-weight: 3500's weigh more than 2500's which drops the mileage some. More "stuff" in the truck which work guys carry should drop it too.
-gearing: 3:55 should be better MPG than 3:73 which is better than 4:10
-manual vs auto trans: as far as I know, manual always beats auto in MPG
-aerodynamics: all trucks are bad at this. But I have noticed that the MPG of my new trucks always get a little worse after I add my step bars, bed cap, ladder racks,etc (wind resistance) Also these things add weight too. Once again dual rears would hurt as they stick out in the air. Also bigger mirrors - bad
-rolling resistance; wide tires hurt here. Same with dual rears. Ever see super MPG contests for "green" cars. They all have really skinny tires - better rolling resistance.

Variable factors are things like city vs highway, weather conditions, driving speed/style, flat vs hills. We see these have some effect but I think the fixed I mention above are more predominant for a given truck. The manufacturers and engine tuners are going to keep trying but I don't think the tree huggers are ever going to see much better than 20 MPG in a 3500 truck or 25 MPG in a 1500.

Sure would be interesting to have database of truck MPG's (avg over one year)with just truck GVW, SRW/DRW, tire size, manual/auto, engine type (gen), gearing, and body add-ons. Ignore the performance mods for this one and just see what the data shows.

 

Oh yeh, forgot the 4x4 vs 4x2. Everything else being equal, 4x2 should always do better in MPG because of several 100 lbs less weight. Add that to the database.

 

This is simple. You left out one important step to it all. You didn't add magnets to the fuel lines to align the molecules or anode rods to the frame to remove the ions that are considered rebel ions and simply refuse to align.

 

You forgot the TORNADO air intake thingy

My dad used to buy any and everything that he could to get his old motorhome better mileage. When you added up the advertised increases he would have needed a trailer to haul the gas it made

I have found that high tire pressure and lower MPH seems to gain me the best increases in MPG. Everything else I have added just sounds better, looks better or makes it get there faster.

 

i used to do this in my gas truck:

use the cruise ALL THE TIME.

i had a full size chebby with the small motor (4.8?)
and it would not pull a greasy string....
and the mileage was crap too.

so I started using the Cruise buttons on the steering wheel.
whenever i am over 35mph, i set it.
that got me 1.5 ~ 2 mpg in the gas truck.
that was in a different town.

traffic is SO BAD here, you can't really do that, but I am trying.

i have two ways to get to work: highway and back roads.
just not stopping on the highway (going ~20mph in traffic vice setting at lights & stop signs on back roads)
usually gets me 1.5 ~ 2mpg gain in my diesel (in my 04 4x4 and the 06 4x2)

i have a spreadsheet over 2 or 3 years of driving you can look at if you want to PM me. there is not much variation, and that variation may be due to under/over filling the tank (if i am in a rush). it only varies from low 15 to 18 or so, best I can see as "correct data"


FWIW, a 3500 only has an added spring pack,
so my 3500 SRW 4x2 Mega with a Tonneau should be a fuel miser.

all the Mega have 2 mufflers: one in regular place, one over axle, plus a CAT.

my 04 had a straight pipe, a K&N and a Bullydog at random times, and the MPG never did vary much.

 

1. Tire pressure near max. Can wear center of tire out faster though.

2. Keep air filter clean. Seems like a new fuel filter helps for awhile too.

3. Drive like there's an egg under the accel pedal.

 

If I want MPGs, I keep the speed at 60MPH and the tires at 80psi, accellerate very gently (keeping the EGT's below 500*) and using cruise control. When I see traffic slowing ahead, I kick off the CC and coast up to traffic. I don't let my ego get between me & MPG's either- if someone wants to snake me as I take off slowly, I let 'em. Chances are they're going to wind up driving faster than my terminal speed of 60 MPH anyway. Doing all this, I can score 20 or 21 MPG depending whether I'm heading to San Diego or LA.

That said, I average 16-18 MPG because I love it when the boost comes up and plants me into that crappy overstuffed captain's chair. I love it when the back tires break free, the engine rumbles its way through three gears, and the speedo says 70 but the forward speed is less than 20. I love the look on the gasser truck driver's face when I come off a light with a 5000-lb trailer and the Dodge's back tires say "ENOUGH of this traction crap, NOW there be SMOKE!!" and they stay lit the whole way across the intersection.

I need a smilie that's a Cummins badge inside a little heart. I (heart) Cummins.

 

I have seen a noticed difference after installing a BAHF and straight pipe, 60 miles more to a tank of fuel.

 

Best way to increase fuel millage is to drive a nail through the underside of the go pedal and drive barefoot. Works great

 

The egg thing doesn't really work as well in these trucks with an automatic. Around here, everything is a hill, so I found that giving it slightly more pedal, getting it up to speed and the tq converter locked up makes a big difference! In mine, with that factory loose goose converter, you can be turning lotsa rpm and not going anywhere, or give it a little more, get it locked and drop 600+ rpm and watch the mileage-o-meter start climbing up. My .02.

Brian

 

I've been keeping records of my fuel economy since last Aug. There is a noticeable drop in mpgs during the winter. When I got my tranny rebuilt with a low-stall billet TC, there was NO gain in mpg! However... Before the rebuild I drove it slower because there was no point in revving the engine and not going anywhere; and after the rebuild I drive it a lot harder. I've noticed there isn't a "huge" difference in mileage relative to how fast I accelerate in the city. On the hwy, there is a noticeable drop in MPG if I drive 65 or 75, about 1-2 mpg.

Finally, I slid my fuel plate and afc housing full forward and cranked the starwheel almost to the end and GAINED an honest 0.5 mpg in the city. That was with a heavy foot too. No joke. Like I said, I keep close tabs on my fuel economy and I guess with the starwheel adjustment, there is a better air-fuel ratio.

 

Finally, I slid my fuel plate and afc housing full forward and cranked the starwheel almost to the end and GAINED an honest 0.5 mpg in the city. That was with a heavy foot too. No joke. Like I said, I keep close tabs on my fuel economy and I guess with the starwheel adjustment, there is a better air-fuel ratio.[/QUOTE]


Thats a very interesting point....Not planting your foot in it before it gets going..I've seen this in some of the gas trucks and cars that I had.The ones with the higher HP and lower gear ratio made better fuel milage for me.It seems you have to match gearing and your motor output..Years ago I had one car and two trucks,all Fords with the 302V8...Those 302 do not belong in a 1/2 ton.One Ford truck I had was a 1/2 with 3/4 suspension,V8 and overdrive auto.My milage was worse in overdrive and the cruise on.The motor was to small and was lugging and downshifting.I really seen a difference on two Pontiacs I had.One was a 1975 T/A,standard 400V8,4-speed and 2.80 rear gears and a 1977 T/A,factory HO 400V8,4-speed and 3.23 rear gears.Beside the night and day difference in power,on the highway the max fuel milage was 14MPG on the 1975 and the 1977 made 22MPG.(sure wish I kept the 75,sure is worth more than what I sold for in 1985..but keep the 77)

 

I noticed my largest gains (2 MPG) when I aired up the tires to 80 PSI and I began cruising at 1800 RPM (about 65 MPH) when I'm on the Interstate (most of my driving).