david85
Full Access Member
I really try to get as accurate results as possible with my truck. I drive the same 200 mile round trip almost every week when work is busy. This allows me to drive the first 100 miles on one tank, then the remaining 100 miles on the other tank going in the opposite direction on the exact same route and average the results.
Thats why I got as high as 24.9MPG, but don't claim that as my average highway performance. Going the other way dropped to 19 and change. Its hard not to stick your boot in it when you can burry the speedo at half throttle
I was able to get the low 20s on rare ocasions with the old C6 transmission too (and no turbo). But that required cool, and VERY humid conditions. Driving through light patchy fog in early autumn. Its not really conclusive, but it strengthens my feeling that mild water injection can help MPGs.
The numbers we see in the duramax seem high at a first glance, but when you consider thats with a 6 speed auto with 5th and 6th being overdrive, its not out of line. They are dealing with a final drive ratio very close to what I have with my single overdrive and 3.08s. The ford 5 speed auto still has the same overdrive as the older E4OD/4R100 tranny.
I've said it before and will say it again. Any stock body diesel (Cummins, chevy, duramax, powerstroke or our beloved IDIs) SHOULD GET 20 MPG if you can get the cruise RPM below 2000. Anything less, and something is not tuned right.
The fact that there are no EPA mileage estimates for these trucks make it a little harder to guess what they should be getting, so threads like this are the only real resource.
Welcome to the forum, Penzanse
Thats why I got as high as 24.9MPG, but don't claim that as my average highway performance. Going the other way dropped to 19 and change. Its hard not to stick your boot in it when you can burry the speedo at half throttle
I was able to get the low 20s on rare ocasions with the old C6 transmission too (and no turbo). But that required cool, and VERY humid conditions. Driving through light patchy fog in early autumn. Its not really conclusive, but it strengthens my feeling that mild water injection can help MPGs.
The numbers we see in the duramax seem high at a first glance, but when you consider thats with a 6 speed auto with 5th and 6th being overdrive, its not out of line. They are dealing with a final drive ratio very close to what I have with my single overdrive and 3.08s. The ford 5 speed auto still has the same overdrive as the older E4OD/4R100 tranny.
I've said it before and will say it again. Any stock body diesel (Cummins, chevy, duramax, powerstroke or our beloved IDIs) SHOULD GET 20 MPG if you can get the cruise RPM below 2000. Anything less, and something is not tuned right.
The fact that there are no EPA mileage estimates for these trucks make it a little harder to guess what they should be getting, so threads like this are the only real resource.
Welcome to the forum, Penzanse