JWR

Gentlemen, thanks for the responses. I have the Cummins 600 with 325 HP, at least that is what was on the sticker when I bought it. Next time I get to the dealership, I'll see if they can run diags to see if something is wrong. As far as drivability, it seems fine.

natebert

Ran ~500 highway miles this weekend.
We averaged 18.5mpg at ~71mph. (kept the motor at ~2000rpms)

If I go above 2000rpms, milage drastically drops. (2200rpms = 75mph= ~16mpg)

~Nate

mestdagh

hmm. 2000 rpms is about 67-68mph for me. Looks like we have the same setup except for you have an auto. I'll have to get some bigger tires

t-15 firefighter

2000 rpms for me is around 72 MPH. i still can't break 18 MPG no matter what speed i run?

you guys that are saying that you can get over 20MPG with a 610 i call BS!!!!

britt

mestdagh

t-7, I haven't gotten over 20 yet either but I don't drive much in the flatlands. I bet I could get 20+ if I drove 60 on I-70 across Kansas. I've only been to Arkansas once but I remember it being pretty hilly. Also you've got 2 strikes against you compared to a lot of these guys. You have an auto and a dually. Both aren't conducive to better gas mileage.

t-15 firefighter

Oh I agree with you.... but my 03 (which was exactly the same as the one I have now except it was a 555 6 SP) would regularly get over 20 mpg at around 60-65 MPH. The freeways around town are mostly flat and I mean flat! I didn't buy my truck for mileage but these guys that are giving these outrageous clams such as over 20MPG with a 610 I still call BULLS*&^ on. They are lying. No other way around it!

Britt

PThree

SRW 1 Ton Auto Short Box and i cant get over 16.5 best so far that was babying it. Also The 72 MPH=2000RPM also

robert chilton

I have the 600 with 10K miles on her and my best milage has been 24.5MPG hand calculated. I have done this twice. Both times were running 60MPH through the mtns of VA and WVA unloaded. However my average is lower at 18MPG because I usually end up on the interstate. On occasions that the diesel goes to work it gets 17+MPG in a 6 mile each way stop and go traffic. That is why I usually drive the gasser to work. Hauling a load on the interstate she gets 11-12MPG. I usually start off in second gear and shift between 1600 and 2000 RPM. Light throttle and staying at 60MPH is the key. I also found that the truck gets better milage in VA than SC by a few MPG. I usually run fuel from BP with no additives. Oil and fuel filter changed at 3000 miles and 7500 from there on. I have not done the milage flash. I know there is alot of info but maybe I stumbled onto something. Good luck with your milage.

grizzlydiesel

I HAVE A 2004 QUAD CAB DIESEL 4x4 with an automatic and 3.76 gears. 325 horses at 2900 rpms is what the side of the engine says. I drive it around town and baby it. I never really get on the throttle and I have only 1070 miles on it so far. The truck only gets 13 and a half miles to the gallon. I was told that the truck would get almost 20. When will this happen?

t-15 firefighter

it won't happen.

sorry to give you bad news.

britt

t-15 firefighter

i almost forgot.... if your truck falls within the sn#'s then you might be able to get the mileage reflash. this will help a little but i doubt it will get you above or anywhere close to 20MPG.

britt

gatf4

You naysayers are making feel lucky I got a good truck. I just filled up today and hand calculated 15.43 for my last tank and that was about 50/50 hwy/city. That included plenty of idle and warmup time too. I am positive that if I went on a road trip I'd be over 18-19 even on the winter blend. Over twenty sounds very possible to me next summer when I get a few more miles on her. I'm only at 8200 now and have had the reflash.

sweetwaterguy

My fuel mileage has improved steadily on my 04 six speed since new--now 10k. I had the reflash done and noticed improvement also. I recently drove 220 miles--all highway and 60-65mph. I hand calculated my mileage at 20.4. My overhead read 19.8. Two recent fillups following my 220 mile road trip--a mostly to and from town were about 18.5, and my overhead was right on target both times. Currently I have 120 miles on my odometer--two 50 mile round trips and the rest in town--all driving conservatively. My overhead reads 20.1. All the above is on winter fuel supplemented with Stanadyne PF.

PThree

I got the flash and have 10k on it. The stupid computer says 21.3 MPG and yes i reset it everytime but hand calcs. Come out differently to around 16.5 at most. Are you people getting 20 filling up to the same spot everytime?

1slow60

I fill up to roughly the same spot every time and usually run the tank down to empty. It usually takes me 32 gallons to fill up. I try to get it almost to the point of overflowing the nozzle once the foam goes down.