Thought I would share some fuel mileage info with everyone.

Went to Indy a couple weeks ago. Ran 64 mph while on the interstate. Total trip mileage was around 370 miles. Hand calculated I got 22.0 mpg. Overhead read 21.4 mpg. I did a little city driving in Indy (30 miles or less). I have a cab high topper on the truck that weighs around 400 lbs.

The truck received the TSB reflash for mileage a few weeks ago. I did see an increase in mileage. Also the overhead seemed off. But recently I have noticed it is quite accurate as long as you burn a complete tank of fuel before calculating mileage.

I have around 16,000 miles on my truck. 4,000 miles of that is with a trailer. Between 3500 and 8500 lbs. So it is most certainly "broken in".

I know many people say fuel mileage will improve after a break in period. Personally I have not witnessed this. If so...it was a very small increase. When I first started driving my truck to work, 50 miles one way, I got 19.2 mpg. This is with only around 500 miles on it. I got around the same mileage until the reflash (around 1000 miles ago). Sometimes I may see 20 mpg...but very rarely.

Just some food for thought....

 

nice to know,

I was thinking that I was going to look for a real good 2003 to ge the 305/555. I was thinking those engines got the best mileage, and they keep the oil, oooh so clean.

But if your getting 20 MPG, that is good. I think pulling iwth a trailer to break it in, is a good idea.

 

Running 65mph empty on level ground, like around Indy, I get about 20+. My work trailer is on my truck probably 2/3rd's of the time. Towing mileage with my 6x12 cargo trailer and about 5-6000lbs, I can get about 15mpg if I run her at about 60mph or so. That's hard to do though; she just wants to run!!!

 

Just a word to the wise. Be careful if you buy a 2004.5 truck. The ones made during Jan, Feb, and March might get considerably less mileage than ones built after March. Mine was built in April. I actually had a truck identical to mine but it was made in Jan. It's mileage was bad and had the misfire/white smoke problem. The dealer order me another truck! Very cool of them by the way! There was a difference between the trucks and even after all the correct TSB reflashes I doubt the mileage would be equal between the two...

 

I have A Jan. built 600,and have never got less than 20-22 mpg at 65. No flashes all stock except some holes in the stock air box.

 

Hmm... this concerns me because I don't think my having the 4.10 rear should drop my mileage as much as I'm seeing. I average 14mpg a tank... 50/50 city/highway.

Best I have ever done is 18mpg, empty, going 55. At 65-70mph I struggle to keep it above 15-16mpg

 

I'm in the same boat I think. I think mine was built real late 04 (have to check again). With 1300 miles on it, I finally managed a 17.6 (hand calc'd), pure highway between 65-70 MPH. Whats wrong with the trucks built in those months and are they (2004.5's) registered as 04's or 05's.

 

OX1....

To me your mileage sounds about normal. Of course I don't have an auto so I am just guessing. The autos may improve with mileage?

doomgaze...what rpm does your engine turn at 65mph? Mine turns around 1900 rpm with the 3.73. Anything above 2000 rpm really drinks the fuel.

jaycoje...well I guess not all trucks are created equal huh? I am glad yours is doing so well!

 

This is bad? I have NEVER seen over 17 mpg on this truck, unless I kept it at 55. Normal highway driving (65-70) I'll see in the 14s.

Heavy truck+dually+4:10 rears = low mileage. I accept it, and move on.

 

Thats what I originally thought since it is an HO, but then I hear from some others they are getting much better. Guess I should just be happy I'm not at the bottom of the milage range

 

I know tons of guys around here that have dodge cummins diesels. All sizes, shapes, some modified, some not. I have owned two dodge cummins myself.

Not one of those trucks or any one I know personally or at least any one that has let me verify their fuel milage get even close to 20 MPG. The normal milage is around 16-18 MPG non towing and 8-12 MPG towing. The towing really depends on wind drag more than any factor.

I'am not saying anyone is fudging their numbers, it's just that out of all the trucks I know no one is making the big numbers some claim on here.

Maybe it's like the old timers use to tell me when I was younger and complaining about having to ride the bus to go to school. They use to walk to school and back uphill both ways and the wind always blowing in their faces.

 

My buddy has an 02, "extended" cab, 4.10's, auto and he gets worse than me @ 25K miles (mainly due to 4.10's I guess) than I get brand new. He also drives VERY conservatively. I think he hit 18 one time, but usually is in the 16 range and 13-14 towing (55 MPH tops).

Then you have another "story" from a friend of a good friend who claims 22 towing 5000 lbs in and around Co. including some of those nasty "pass's" (this was a 6 spd truck I believe).

Maybe the next largest factor beyond wind drag is the tranny type??

 

Gotta say I agree with that. I would like to see how some of these numbers are calculated. It seems as though my overhead is pretty close to accurate, and why would it not be. Sunday I drove about 800 miles with just a motorcycle in the back and would reset the computer once I got up to speed on the interstate. On the way home, driving through IL I was getting around 19 or so, and that is about as high as I have ever seen.

 

I think I turn about 2200rpms at 65mph... or somewhere close to that.

Seems like wexman and I are seeing the same numbers.

 

There is no difference between an 04.5, 05, or 06 for that matter as far as the engine goes.