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The mileage you guys are getting with your higher-geared rear ends is killing me - as is my lift with 255/70r22.5 wheels... ((-: But seriously, I have a 2012 F450 CC LB DRW 4x4 with a 6" Icon lift riding on 22.5" American Force wheels and the aforementioned Sumitomo commercial truck tires. Towing a 10,500# boat trailer on flat ground at 65 mph I get 10 mpg (avg. was 8.3 incl. town and launch). Empty around town I average just under 10, on the freeway about 12.5 mpg. The truck has just under 32,000 miles on it. But this is not my daily driver, so I don't really care. The truck does what I bought it for and it does that well.
Best mpg I ever got since new had always been 17-17.5 on hwy and empty, even with cetane boost added. I recently spent a month traveling around Utah and put on about 4000 miles towing. I didn't much pay attention to mpg during towing but sure as hell burned through alot diesel and benjamins. After arriving back home (nothing done except added more DEF) and taking another short trip, all mostly flat highway but not towing I'm now getting 22mpg running 65-70mph. This was consistent after burning through 2 tank fulls and no cetane boost added. Lie'ometer says 22.5 and manual calculation gives 22mpg. I use the same fueling stations.
Can anyone explain why?
Truck is in my sig., use 5w-40 Rotella T6 and have 45K miles on it. In the meantime I'm going to continue monitoring closely.
Just posted this in another thread ---
2015 F350 4x4 CC DRW 3.73 gears. This truck is still breaking in as it only has a little over 1,000 miles so far.
17-18 unloaded
8.5 avg towing ~17,000# high profile 40' Toy Hauler @ 65mph.
I expect to pick up another 1-1.5 MPG after it is broken in.
Love this truck...
The guy who's driving style is jack-rabbit starts and panic stops pays dearly.
The guy with gradual starts, lots of foot-off-the-pedal and looking down the roads stops will achieve much greater economy.
I would dare to venture that for most drivers, it's an emotional issue and pretty much brainless in terms of operational characteristics.
Check me if I'm wrong, but it looks like one would have to value their time above $27.00 / hour (and their health somewhat less) in order to justify the higher speeds.
The guy who's driving style is jack-rabbit starts and panic stops pays dearly.
The guy with gradual starts, lots of foot-off-the-pedal and looking down the roads stops will achieve much greater economy.
I would dare to venture that for most drivers, it's an emotional issue and pretty much brainless in terms of operational characteristics.
Check me if I'm wrong, but it looks like one would have to value their time above $27.00 / hour (and their health somewhat less) in order to justify the higher speeds.
Just curious. Is there a vortex between 65 and 70 mph?
Speeding up by 5mph generally equates to a loss of .6mpg. But from 65 to 70, it's 1.1 mpg.
1) Increasing air resistance. According to CNN, "Pushing air around actually takes up about 40% of a car's energy at highway speeds. Traveling faster makes the job even harder...The increase is actually exponential, meaning wind resistance rises much more steeply between 70 and 80 mph than it does between 50 and 60. "
The guy who's driving style is jack-rabbit starts and panic stops pays dearly.
The guy with gradual starts, lots of foot-off-the-pedal and looking down the roads stops will achieve much greater economy.
I would dare to venture that for most drivers, it's an emotional issue and pretty much brainless in terms of operational characteristics.
Check me if I'm wrong, but it looks like one would have to value their time above $27.00 / hour (and their health somewhat less) in order to justify the higher speeds.
And if you believe all that, you should look into fueling up at night when the temperatures are lower and the fuel is the most dense. According to the same math as above, you will save a ton of money by buying your fuel when it has contracted at lower temperatures and then expands while you drive at higher temperatures. It's cheating the system man!
Who burns $38,000 worth a fuel a year in one vehicle?
And if you believe all that, you should look into fueling up at night when the temperatures are lower and the fuel is the most dense. According to the same math as above, you will save a ton of money by buying your fuel when it has contracted at lower temperatures and then expands while you drive at higher temperatures. It's cheating the system man!
Who burns $38,000 worth a fuel a year in one vehicle?
That's missing the point. This thread is about real world mileage.
Real world mileage can vary widely. Dually, SWR, speed, rear end, etc. - but speed especially is important.
The example would be extrapolated to more realistic "average" type driving.
Every 2% reduction in aerodynamic drag results in approximately 1% improvement
in fuel economy.
Above 55 mph, each 1 mph increase in vehicle speed decreases fuel economy by
0.1 mpg.
Worn tires provide better fuel economy than new tires, up to 7% better fuel economy.
Used lug drive tires can get up to 0.4 mpg better than new lug tires.
Ribbed tires on the drive axles provide 2–4% better fuel economy than lugged tires.
Every 10 psi that a truck’s tires are underinflated reduces fuel economy by 1%.
The break-in period for tires is between 35,000 and 50,000 miles.
Tires make biggest difference in mpg below around 50 mph; aerodynamics is the
most important factor over around 50 mph.
The most efficient drivers get about 30% better fuel economy than the least efficient
drivers.
Idle time is costly. Every hour of idle time in a long-haul operation can decrease fuel
efficiency by 1%.
Professional big rig drivers will support this information as well. For an interesting read on fuel mpg drift on over to POST #6 at TheTruckersReport.com
09-16-2014, 06:48 PM
