What is your best (repeatable) MPG with an 04.5 600?

[klenger]

This is a repeat of the poll I posted on 04-08-2004 . Now that we have some more miles on our trucks, and more members have taken delivery of 600's let's try the poll again. If you voted in the previous poll, you are encouraged to vote in this one also.



Enter your best milage that you calculated under normal conditions, rounded up or down to the nearest 1 MPG. Let's not use numbers like 26 MPG coasting down I-70 into Denver for 40 miles or readings from the overhead computer, but stick to realistic numbers that are repeatable. "Be honest, this is for posterity" (from "The Princess Bride). The results of the poll will be a bit misleading since there are so many truck configurations that affect milage, but it should help see the range of numbers. Feel free to make any comments.

 

[NDanecker]

See below for hand calc since new which includes some towing, warm ups, going to Wawa for milk, etc.



Running on the highway empty on long trips at 65mph I can break 18 without a sweat. Its the around town and speeding (75mph+) that kills my mileage. I've never owned a truck before that had its mileage vary so much just by varyng its speed from 65 to 80mph.

 

[DPelletier]

I just instructed my Superintendant to record a fuel log of our new 600 over the next few weeks. It'll be run 90+ percent highway at light or medium load. Should give me some data to compare to my 555. I'll also be checking the 600 every 5,000 miles or so, so I can get a feel for the effects of break in vs. mileage. I'll post some results when I have them.



Dave

 

[JohnnyH]

My average is 18. 5 MPG with mixed driving. I have just over 3000 miles on the truck, with no towing yet. I voted in the 19 MPG box.

John

 

[swexlin]

Getting close to 13 now puttering around town, where as before I got mid 11s -12. Maybe a couple of reasons for this:



1. My evening commute, on nights I don't go to the gym, I'm taking a slightly longer route, but less traffic and traffic lights.



2. No more winter-blend fuel. (That was always good for 1-1. 5 mpg right there in my Ford).



3. Tonneau cover (interesting that my mileage got better around the same time this went on). Maybe just conincidence. I have had tonneaus on all my trucks, and they have never made a difference.



I have about 3200 miles now - not even to first oil change yet, which I'm planning on every 5000 miles.

 

[HOCummins04]

I am currently on vacation in Indiana, and will see all you guys at THUNDER IN MUNCIE in a couple days.



I live in West Virginia. Left home with 2000 miles on the clock. Basically had driven truck back and forth to work. Have been averaging around 15. 75, depending on how much I play with the ever increasing power. My trip out here mileage kept rising at each fillup. I went down to Columbus Indiana to the Cummins MidRange Engine Plant for a tour the other day. Truck was empty except for me and my dad. I65 speeds of 65 to 70, using cruise control. Best MPG so far is 19. 7 hand calculated on that trip. Have 2700 miles on the clock now. Just keeps getting better. Though the overhead for that trip showed 15. 7, it is still reading 15. 5 - 15. 7 around town, so it appears that my mileage is still up pretty good. Though there are times where I make liberal use of the power, I generally operate my equipment at a fairly easy pace. I know my 6 spd is not as fast from a light as an automatic, and don't try.

 

[doldenburg]

13-14 empty. had trailer withanother truck the other day- 7. 6!! it sucks. I don't think it has the advertized hp-tq either. took it to the dealer but they say nothing wrong, the expected answer. I like my gen 2s better.

 

[jstrong]

I have been between 14 and 15 hand calculated. I do about 85% highway driving usually around 65 to 75 MPH. Every once in a while I will toast one of those little Rice Burners just to show them they have nothing under the hood!!!!:-laf:-laf I aired my tires up to 65PSI a couple days ago and the over head computer has been averaging around 17 to 18 MPG. I will find out if it has improved the mileage. Tires were at 55PSI before.

 

[TX Gooseneck]

I can't get one tank even close to another. If I stay out of it I'll average anywhere from 16. 2-17. 2 and if I'm driving like I typically do, between 14. 5-15. 5

 

[stevenknapp]

I aired my tires up to 65PSI a couple days ago and the over head computer has been averaging around 17 to 18 MPG. I will find out if it has improved the mileage. Tires were at 55PSI before.



Let us know, I'd be really interested to find out if that 10PSI really up'ed your mileage!

 

[smithinc]

i get about 19 mpg hwy with 65 psi in all tires and at or under 2000 rpm empty. 3800 miles on truck



gary

 

[NDanecker]

Originally posted by stevenknapp

I aired my tires up to 65PSI a couple days ago and the over head computer has been averaging around 17 to 18 MPG. I will find out if it has improved the mileage. Tires were at 55PSI before.



Let us know, I'd be really interested to find out if that 10PSI really up'ed your mileage!

I increased my tire pressure from 45 to 60 as a test. I just got to Atlanta, GA from NJ (approx 937 miles) and I've seen a little over a 1 mpg increase in mileage. I can't believe 15 psi makes that big of a difference.



Overhead shows about the same increase... . and is pretty accurate to hand calc.



NJT

 

[klenger]

With 62 votes right now, 82% are getting 15 MPG or better. These are much better numbers than what the poll in April produced.



"That thing got a HEMI in it?"

 

[FJfonda]

13mpg empty average for the last 3000 miles although the last 2 tanks hit 13. 5mpg. I just rounded 5000 on the clock and have been cought doin' the granny takeoffs trying to get good mpgs. Ever try keeping the boost under 15 psi. . all day? If you do... don't look behind you as the line will be verryyy long. Towing 12K lbs less than 100 miles on a tank drops my average below 10mpg. Towing for a full tank will be scary. I am expecting 7-8 mpg. This is all hand calc (spreadsheet actually) with front tires at 75 psi and rears (DRW) at 55 psi. My '99 DRW QC 4X4 5sp ran 18-20 mpg empty and 13 mpg towing the same 12K lbs.

Hope this improves.....

 

[CAgnoli]

I chose the 17 on the poll becuase I average 17. 6, 9600 miles on the truck, with a mix of 80% highway, 20% city. This truck is my daily driver, and I commute 97 miles one way to work.



With that said, I've noticed the trip computer shows as high as 19. 2 if I fill up next to the highway, and stay on the highway for 44 miles, then I'm back in traffic, and it starts the downward cycle. I'm taking a trip to NJ in three weeks, all highway, and can provide data on a full tank ALL highway, but it seems that 17 to 18 is the magic number for my truck, bone stock. (Hand calc each time)



I'm slightly disappointed, as I was hoping to get in the 20-22mpg range with a CTD. Guess I bought it a couple months late.



If the removal of the Catalytic converter actually increases the mileage 2 to 3 MPG, as some seem to suggest, it might pay to pull if off. As it is, I'm tempted to run the red stuff at 1. 23 a gallon

 

[KBertetto]

I can consistently pull between 21 and 23 mpg depending on wind and road/highway conditions travelling between 60 and 65 mph, empty of course. In town it's a straight 16 mpg, if I keep my foot in it I can get it down to 13 or so. And of course, all figures hand calculated, generally 1-1½ higher than the overhead, and I always fill up at the same station to the same spot in the fill tube.



Bert

 

[Torque King Jay]

I've got about 1700 miles on the odometer and overall the mileage has been good. Picked the truck up from Tomeygun in St. Louis and drove it back to Cincinnati, OH. Filled the tank up and the hand calculation was 16. 72 (overhead was 15. 4). Second fill up hand calc was 17. 71 (oerhead was 15. 9). Short filled it (because fuel was cheap at that time) hand calc was 18. 2 (overhead was 16. 4).



Considering I haven't towed a single thing with it, and there is only 1700miles on it, the mileage has pick up significantly. First fill up was pretty much all highway, second fillup was 70% hwy and 30% city. Maybe if I work it the mileage will pick up quicker. I don't expect this rate of increase to last for ever but I'll take what ever she gives me. If I could get 19 or better I'd be happier than a pig in ***#. I'm getting ready to install my tonneau cover this week. I wonder if it will help. BTW fron tire pressure is 65psi rear is 55psi ( I think I'm going to air down to 48-50psi in the rear the ride is a little harsh.

 

[smithinc]

filled up in hagerstown, md yesterday afternoon and drove 120 gallons ( 1800 #) of traffic paint to pittsburgh, pa. i did the speed limit the whole way, between 55 and 65 mph. dropped off the paint and drove home again at 55 to 65 mph. ended up at 20. 2 for the whole trip of about 400 miles.



gary

 

[klenger]

ended up at 20. 2 for the whole trip of about 400 miles.

Most excellent Oo.

 

[stevenknapp]

A friend of mine just loaned me the March 04 issue of trailer boats. It's got a interesting non-diesel-specific section on axle ratios and MPG. Interesting read, lots of input from GM engineering.



The short of it is that the axle ratio makes less of a difference than driver style and speed. They also mentioned that a gasser at 50-55 gets much better mileage than at 70-75. I forget the exact numbers, but it was something like 17 vs 14MPG.



"Trucks are the most sensitive vehicles to real-world driving conditions... there fuel economy is considerably more sensitive than that of cars. . vehicle speeds, not axle ratio, plays the biggest role" Roger Clark, senior manager for GM's Energy Integration and Fuel Economy Learning Vehicles.



I know it's a "duh" but it's an interesting read none the less.