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Mileage at 1600 rpm (58 to 61 mph) was 21.7 mpg
Test route was 42 miles by freeway one way - then 42 miles back on the same route with cruise control set most of the way.
No wind. Light to moderate traffic traveling within 10-percent of 60 mph most of the route.
Method was to get on freeway and up to speed, reset the lie-o-meter to zero, drive the 42 mile distance and check mpg at freeway off ramp: 21.9 mpg.
Repeated process on return route. Got up to speed, reset the clock, drive the 42 mile return route and check mpg at freeway off ramp: 21.6 mpg
I drive this route several times a year - the route is mostly long gentle inclines and flat - 6th gear at all times.
I did the same test with my 2005 6.0 ten years ago (same basic truck) and got 22 mpg.
My driving style is a real feather foot and cruise control.
This is probably the very best mileage that this particular truck will ever get.
How many miles on your truck?
Regens is what REALLY messes up good mileage.
With just over 1,000 miles on mine, hwy mileage is just under 18mpg at 65 mph and 60 PSI in the tires.
Edit - I have 3.73 gears also and the Highway radials which will also make a difference..
The purpose of this particular test was to see what the truck is capable of "at speed".
This is in comparison to a test that was performed on my 6.0 dually 4x4 3.73 many years ago.
It is somewhat ingenious to comment on the "start" acceleration component as that belongs to a separate test that does not include "at speed" testing.
Personally, this is a comparison test and serves as a basis point for future repeatable documented trials of this truck.
Those driving single rear wheel trucks or those with duallies and two wheel drive should ignore these result as they will not reflect "apples to apples" results with other equipped trucks.
The truck just turned 1000 miles during the trial. No regen occurred during that time.
Normally, the truck will be run at over 14,000 pounds GVWR and pushing a lot of air down the highway.
The old 6.0 with the same carrying load average 11.6 mpg loaded. I'm guessing that the 6.7 will probably give me about 11.5 mpg
The starts are important. When my wife is traveling with me, we make more stop breaks and I've noticed that mileage suffers (with the 6.0)
When I drive alone, I'll run through a tank and only stop for refueling. Gets better mileage that way!
Bigfoot: I forgot to check air pressure! Normally, I'll keep them at 80 pounds all the time.
(today added a pair of 5000 lb SuperSprings and Rancho 9000's to the rear axle.)
Heading over the North Cascades Highway this weekend. Should be interesting.
Last edited by pacnorwest; 10-08-2014 at 09:27 PM.
Reason: oops
5800 pounds in the bed of the truck. Height is approximate 11' 6"
About the size of a barn door goin' down the freeway sideways.
Your 13' height is what's killing your mileage - that plus speed.
My old 6.0 rig would get an average of 11.6 mpg at 62mph - that's averaged over 85,000+ miles including stops, mountain ranges, open highways, etc.
Driving that rig into wind would quickly drop mileage into the 8 or 9 mpg range.
I don't expect to learn much about mileage this weekend since it's mostly mountainous driving.
However, handling, brakes and . . .woohoo! EXhaust Brake testing is anticipated.
I'm not really concerned with fuel economy while towing. I am more concerned about the truck's ability to perform and safely drag the load. It has both of those covered in ACES...
You are going to love that exhaust brake... Trust me!
5800 pounds in the bed of the truck. Height is approximate 11' 6"
About the size of a barn door goin' down the freeway sideways.
Your 13' height is what's killing your mileage - that plus speed.
My old 6.0 rig would get an average of 11.6 mpg at 62mph - that's averaged over 85,000+ miles including stops, mountain ranges, open highways, etc.
Driving that rig into wind would quickly drop mileage into the 8 or 9 mpg range.
I don't expect to learn much about mileage this weekend since it's mostly mountainous driving.
However, handling, brakes and . . .woohoo! EXhaust Brake testing is anticipated.
2005 6.0 dually sold at 112K
That's a sweet looking slide in, would you mind sharing a few pick's of the inside? I'm in the market for a slide in.
Beauty of a slide in camper!! I had put aside my thoughts of getting one, but now you have my interest up again... Now I need to trade up to a dually...
10-08-2014, 09:18 AM
.....we wish...
