yermn

Just a brief history. I currently own a 2003 2500 4X4 5spd hemi that gets on avg as per overhead computer 12.2mpg. I have finally convinced my wife that I need a Cummins. After 12 years she has given me the green light to order the truck of my dreams. She was swayed due to my argument that I can save at least 30% fuel cost by going with the diesel. This amount I thought was very conservative. So off to the dealer i go and order on Mar 13 a 2004.5 2500 4X4 6spd SWB Blah Blah Blah. Needless to say I was very excited. Now i start to find out more information to reaffirm my desicion only to find one major concern. Why are so many people with 600s getting such poor fuel economy. I was hoping that they were wrong or just very unlucky. But I should have known better. Today i went to the local dealer and was able to drive both the 600 and 555. I first took out ta beautiful black 600 4X4 dually with only 22kms. I reset the trip meter and proceeded to go for a 10km drive. At first the numbers showed 3.9mpg and were moving very slowly. I got a best of 11.9mpg. I was shocked and very dissappointed. Then for comparison i took out a 2004 2500 4X4 555 with 20kms on clock. I reset the computer and drove the same route and immediately noticed how much quicker the numbers rose on the computer. They peaked at 19.1mpg. Gutted and now very confused and even angry. How can such a difference exist. I informed the dealership of my concerns and told him what i had been reading on the various Cummins Diesel sites. It was the first he had heard as far as poor fuel economy for the 600s. Now i am going to tell my dealer that when my truck comes in i am not signing anything without a long test drive to see what kind of mpg it will get. If i don't see at least 16mpg I am not getting the truck. I will be greatly dissappointed after having waited so long. If you guys no of any fixes or information that would help i would be greatlful.

Jonesey

yermn,
I wouldn't be too concerned about the displayed MPG. Did you reset both overhead computer's MPG before you drove them? If not someone with a lead foot who test drove the 600 before you could be the culprit. Regardless you need to have much more than twenty-thirty mile runs to get a realistic average.

Dude don't blow it! You have the little woman convinced. The added mileage is great but it's not everything. It's a diesel thing. Once you get one you will never go back. These are 7800 pound vehicles and get great mileage no matter what with that in mind. It's your dream truck! Ask your dealer to let you keep it for the weekend and see if it gets better. They definitely all do after 15-20K. Another thing would be did both trucks have the same gearing? From what I have seen most reports for identically geared 555s and 600s state about 2 MPG less for the 600s.

phox_mulder

Have to remember that it takes around 20,000 miles for the Cummins to get broken in.

Mileage will go up and up from that first test drive.

Mine's approaching 30,000 and it is still getting better, albeit more gradually than at first.


phox

Sittenbull2

You know you ain't gonna see alot of mileage at first it will come with time and miles. My truck I saw 13 to 14 mpg. in the very beginning now up to 17 to 18 mpg with 28,600 on the OD. I know some get great mileage right off the lot but I didn't. If it is any comfort to you

03CumminZ4X4

Grab the 555 thats meets your needs closest (they are getting scarce new) and run. I almost didnt find what I wanted in a 555 on 3-31-04! The KITTY (emissions crap) on that 600 is tryin to get you and your wallet! Good luck!!

BiggRigg600

Yermn,
I did the same thing, convinced the wife to let me get a new diesel (I've wanted one for a long time) to replace my thirsty 1500 w/360 V8 because of it's pitiful milage (13 coasting downhill with a tailwind). My new 04.5 2500 4x4 600 auto so far is only getting in the high 12's... driving grandpa style and although it is new, I expected a lot more after reading up on these things over the last couple of years. I'm told it will get better after break-in, but that's going to be hard to convince the little lady of that one. Also, when you do your test drive, get that sucker up to 70mph and beyond to see if it vibrates/resonates like so many of ours are doing. I live in AZ and most of our highways are 75mph so it makes it almost unbearable to have spent almost 40K on a new truck with these problems... I sure hope they have a fix soon before I cry lemon!! ~I'm not trying to talk you out of it, just my .02... I wish I would have found this site before I took the plunge.

Cheers

BigCarl

Find a 305/555 04 model if you can. The injection sequence is different on the new '600' Cummins to meet new EPA emissions standards as well as a new catalytic converter. MPG efficiency and stronger emission standards do not mix!

Vaughn MacKenzie

I have seen a number of posts (mainly on TDR) of guys getting decent mileage with their 600s (high teens) but after all the reading I would say the 600s MPG early average is roughly 10-15% worse than the HO 305/555. My guess is the extra post-combustion injection event is part of the reason, and maybe the timing is more retarded or the main injection event goes further into the combustion stroke and wastes fuel.

I would lean toward finding a 2004, but I wouldn't write off the truck you ordered necessarily. Yermn what configuration did you get??

Vaughn

BASSMAXX

yermn,

I am in the same boat as you. I just got back from a dealer and driving a couple of trucks to narrow down/confirm my choices.

I also posted a poll to see what the 555 guys are getting for mileage. Looks to be a lot better than the 600s, and even 15% is a lot of fuel over a few hundred thousand miles.

My guess is you are in Canada, although you didn't say, but for anyone looking for a 555, it seems there are plenty here in Texas. And they are being sold, by one dealer at least, for $300.00 below invoice. I'm going there tomorrow. Wish me luck.

With regard to your wife, you know her better but I wouldn't want to have had convinced my wife that a very expensive truck would pay for itself in fuel savings and then be proven wrong. Would she ever let it go?

One more thing: This dealer I went to had a sales guy who said there was a mopar black box that increased HP and TQ and delivered +- 4mpg better milage and it didn't (of course, because it was from Mopar) void the warranty. Anyone know what he's talking about, or is he talking out his @$$.

________________
For the record: White Ram Sport 3500 LWB, QC, 48RE, 2WD hopefully in a 2004 555.

bulabula

He was blowing warm air up your skirt for the sale. Did he know that Cummins is spelled without a "g"?

FWIW, my last couple of tanks were in the 19.2 range; 50/50 city/highway. The Overhead readings were in the 19.4 range. Those figures were accomplished by keeping the engine under 2K during normal driving. That means 62'ish on the highway. If I notch it up to 70-75mph cruise, the mpg numbers fall into the 17 mpg range.

dwhite

yermn, you are doing the right thing. Do a long test drive and make your decision. I don't understand something here...do some people think that the 555's "don't break in" or what. I have seen many posts where they tell 600 owners to "wait till it's broke in" but.....if both the 555 and 600 improve with break in then I would take the extra 4 to 5 mpg (or roughly 140 to 175 miles per tank farther).

C'mon guys why can't you admit there is a problem here?

GrandpasRam

If you're talking a daily driver with some towing, I'd get the 555. The extra 45 lb/ft is not worth the loss in mileage I've seen posted here. Having said that, I also would not hesitate to get a 600 if my truck got totalled in an accident. The mileage will increase with break-in, and there are always a few relatively inexpensive things that can be done to improve mileage such as a Ram Air III air box, dropping the exhaust for an aftermarket, etc. Given a choice, I would try to find a replacement 555 new on the lot, but if that weren't productive, I would have no problem getting the 600 and doing a few things to it after break-in. Good luck in you're choice.

Jonesey

My post stated that they all get better mileage after 15-20k. The key word here is all, meaning both the 555s and 600s. I just mentioned it to let yermn know that which ever model he chooses it will get better after it is properly broken in. I would hope that it would get at least 2-3 more MPG after being broken in.
Is there really a problem or is the lack of mileage just a result of the pollution controls? If you are interested in nothing but mileage the 600 may not be for you. It will take many miles and years before you recoup the price difference between a gasser and the diesel, whether it be the 555, 600 or any of the other brands. These trucks accel at towing heavy loads.

dwhite

The problem I am referring to is the problem that DC is going to encounter when their sales fall off when the consumer finally realizes how much he is losing by getting the 600. The main problem is the transition to emission requirements has not been "advertised" to the consumer. Even their commercials try to lure people to the "class leading 600ft/lbs of torque". 5 years down the road you won't be able to have a choice of"555 or 600" so there won't be all this discussion. I just want to tell people so they don't have to make the same mistake I did. As for me...I hope DC can do something about it because I won't be satisfied till they do.

jlasich

I don't think that's going to happen because whether the Cummins gets 12 mpg or 20 mpg, it's still a better engine than the other 2 choices (although the Duramax is doing really well; you couldn't give me a 6.0l PSD). To me, fuel mileage is a very small part of the total package. Having a reliable, dependable, easy to work on, no glow plug engine is far more important.