04.5 Cummins 600 Milage Update

[klenger]

I have some (at least to me) good news about the mileage on my 04. 5 Cummins 600.



First: I made a short 52 mile trip tonight, filling at the same pump before and after the trip. Driving 60 +/- 5 MPH, mostly highway, the overhead computer showed 18. 3 MPG and the calculated was 17. 45. I realize that 52 miles is too short to get a real accurate measurement, but the numbers are encouraging.



Second: Below is a snapshot of the Excel worksheet summary that I use to keep track of my mileage. The interesting numbers are at the very bottom. If I enter in an estimated mileage (MPG) for towing my camper, and then have the worksheet recalculate the mileage for running empty, I get the results in green at the bottom of the chart. From my experience with my old truck and this one, my towing mileage is usually between 10 and 11 MPG, so the numbers in green should be pretty close.



The calculation for running empty is done as follows:

Fuel Used Towing = Towing Miles / Estimated Towing MPG

Fuel Used Empty = Total Fuel Used - Fuel Used Towing

Miles Running Empty = Total Miles - Towing Miles

Empty MPG = Miles Running Empty / Fuel Used Empty



I expect these numbers to improve with more mileage, the ECM reflash (which I do not have yet), summer fuel, and synthetic oil after break-in. The punch line is "I think I got a good one, and I don't think the 600 is inherently poor on fuel consumption".

 

[thames1948]

WOW, thats the best post I have read in awhile! I only have about 700 easy empty miles on mine, so maybe there is hope after all. Everything else so far has been perfect. No miss, vib's. drives straight as an arrow. What mpg numbers did you start out with?

 

[DPelletier]

Good job, Ken,

and FWIW, I expect that the 600 will prove to be as good as the Cummins' to come before it.



Dave

 

[Hawkeye 04]

I forfeited the 20 extra hp for the fuel mileage and bought a Tomeygun Special and am VERY happy with it! I've had it only a week and a few days and already have 2500 miles on it! Yesterday I went on a 300 mile trip on secondary roads with top speeds at 70 mph and through about 10 little towns w/stop and go at every town. I got back and filled up and my overhead computer was only off by . 2 mpg. I averaged 19. 8 overall and my very accurate computer was saying that on the flats i was getting 21 mpg... with only 2500 miles! I'm very happy but I think that the 600s will get up there to with some time and re-flashes.

 

[thames1948]

I've got my fingers crossed that DC hasn't given up mpg's to be ahead of the rest on power and torque. Well aleast not that many I would be happy to get what Klenger is getting.

 

[bish777]

Filled up today, 525 miles on the tank of fuel. By hand it was 17. 8, on the overhead computer it was 16. 5. The tank was a mix of hwy driving @ speeds of 70-85, city driving, stop and go, and pulled my boat about 20 miles. I have 3500 miles on the truck now.

bish

 

[carson6]

I have 200 mile's on mine

 

[BIG BOB]

I certainly don't want to put a dimmer on the good info you guys are reporting, however I have one question for you.



With having to baby feed the last 4+ gallons diesel into the fuel tank, I've put as much as 5. 5 gallons in after the pump shut off. Are you topping of the tank off completely into the filler and then doing you mileage test?



If not, you will not get an accurate MPG. I know, it's not recommended to fill into the filler tube, however starting out with a full tank and filling it up to the exact same place is the only way you will know that you will get an accurate MPG. With the variable of being able to add 4+ gallons after the pump shuts off will give you inconsistent MPG's if you don't fill into the filler tube.



Alright, fire suit installed. :-{}

 

[PJ]

That looks respectable. My 305 hp got 21 mpg on the first tank but that was doing 65 on a 250 mile run with no stops. My avg is about 17mpg with 50/50 highway and city.