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Old 02-18-2012, 06:11 PM   #11
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Posts: 755
Originally Posted by Rebel702 View Post
Two follow-up questions:
1. Do you use cruise control when towing?
2. How often do you use the engine braking (for the diesel owners)? Does this help or hinder mpg? (I know it does help save the brakes. I used engine braking coming down out of Flagstaff with the TT and it was a nicely controlled ride and worked great with the cruise.)
Background - 2011 Dodge 6.7 Cummins, 6 speed manual transmission, Crew Cab, Long Bed, Trailer is Wildwood 25BHLE (GVWR 7680, 26ft)

1. Yes I use my cruise control towing when conditions permit, which with my setup is most the time. Exceptions - winding roads, mountain highways, grades. I feel I have better control without it in those conditions, this includes being able to brake for critters who appear on the roadway,

2. I use the exhaust brake most the time, towing or not, with the manual transmission it is amazing how great it works, even with daily commutes. I don't think it has any factor on the gas mileage as it only engages when the your foot is off the accelerator. While towing, I can descend most grades without touching the brakes while even passenger cars and SUV's (not towing) are riding their brakes. I would never want to go without it again!

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Old 02-18-2012, 06:57 PM   #12
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Join Date: Aug 2009
Location: Sudbury, Ontario, Canada
Posts: 90
Someone mentioned a spreadsheet for calculating, and I have been using one for my last 2 trucks from this site: Downloads - Backgrounds, Screensaver, and more

The spreadsheet are in Excel and are free to download, it gives you measurements in both US and Metric. I use the metric, because Canada in using metric, but it also converts back to mpg for us old folks who are having trouble learning metric.
Anyway, this is an excellant spreadsheet.

2009 GMC Sierra SLT Crew Cab 4x4 Diesel
2010 Rockwood 8280SS

Camping 2012: 40 nights
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Old 02-18-2012, 08:19 PM   #13
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Location: Calgary, Alberta
Posts: 358
Originally Posted by Rebel702 View Post
Accountant by trade so I am pretty anal about keeping a spreadsheet. I am right at 30 fill-ups with an average 14.3mpg calculated to the computer's 14.42mpg. Worst mileage was 8.1 over my trip from MO to Las Vegas w/ the TT and fighting 35 to 50 mph headwinds.
On the trip back from SLC cruising at 75 and I still had guys riding my bumper
I've been using an iPhone app to do all of my calculations since I bought the truck and my numbers are right in line with yours for overall average.
26WRB - V-Lite
Denali HD LML
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Old 02-29-2012, 07:47 AM   #14
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Location: Rio Grande Valley Texas
Posts: 357
Keep in mind if you increased tire size from the factory itty bitty pizza cutters that GM puts your MPG on the computer will be off. You need to use a programmer to let teh computer know the new tire size.

Ruben Zamora
2007 Silverado 2500HD 4x4 Dmax/Allison, 4" Exhaust-no cat-no muffler
2012 Palomino Puma 23FB
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Old 03-03-2012, 09:47 PM   #15
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Join Date: Apr 2011
Posts: 97
I reset my computer before my trips, Canton OH to Myrtle Beach + or - 640 miles , driving around 60-65 I can get close to 12, hauling ***** and I'm in the 10's. No trailer, computer reset is right up to +22. 31 foot Flagstaff classic TT, 2011 Duramax crew cab, just under 17K gross.

Mike & Lu Anne
& our Jack Russell 'Genny'
2011 Flagstaff 831FKBSS
2011 Chevy CC Duramax Z/71
OH plate GM DMAX
Hensley Arrow
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500, diesel, gmc 2500hd, mpg

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