MPG to expect

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My son has a F250 that gets 17 town and 20 hiway unloaded and he drives it hard.  It's a 2004 model, and, he's had it modified to have even more power/torque than stock, so it would probably get better MPG if it were stock. FWIW.
 
I drive a 2008 F250 with diesel and get fairly decent mileage based on this thread. Unloaded in the city I get about 12 mpg on average. On the highway with my 5er I get between 17 and 18 if I keep it on cruise at a legal speed. With my 2009 Komfort trailer at about 12000 lbs, I get between 9 and 10.5, again with cruise on at a legal speed. Strangely enough, I get better mileage with my new 5er at 12,000 lbs than I did with the travel trailer I traded in at 8,000 lbs. Must be the aerodynamics of the new trailer.
A curious question......do the wind deflectors I see on the roof of some pickup help?

Bob
 
The newer diesels took a  hit to fuel economy as a result of new pollution measures, so a late model diesel will get poorer mileage than an '04. Ford in particular seems to have lost mpg when they changed from the venerable 7.4L Powerstroke to the new 6.0 and then 6.4L engine.
 
A curious question......do the wind deflectors I see on the roof of some pickup help?
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The short answer is "no, probably not".

Long answer: A properly designed wind deflector could make an improvement, perhaps a major  one, but it would have to be set up in a wind tunnel and designed for the air flow around your particular rig. The chances of buying an off-the-shelf deflector, setting it up by eye, and getting much improvement are slim at best.  I am reminded of the ventilated truck tail gates that were the rage for awhile. Seemed obvious they would allow a better air flow and improve mpg, but for most trucks it was later shown that they either did nothing or even hurt the mpg slightly. A truck bed cover, on the other hand, was found to slightly help aerodynamics.
 
Thanks Gary for your response. Just my luck to buy a 2008 F250 and get less mileage. I undestand that when the filter gets cleaned, I lose about a gallon of diesel fuel. Not good and the EPA stuff cannot be disconnected by anyone I know.
Thanks also for the info on wind deflectors. I see them often and have wondered if they were of any value.

Bob
 
Bobandpamlemay said:
Thanks Gary for your response. Just my luck to buy a 2008 F250 and get less mileage. I undestand that when the filter gets cleaned, I lose about a gallon of diesel fuel. Not good and the EPA stuff cannot be disconnected by anyone I know.
Thanks also for the info on wind deflectors. I see them often and have wondered if they were of any value.

Bob
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There are "folks" around that can make "improvements" using a different chip and what not.  It's risky though in terms of your warranty and would probably affect the emmissions from the engine in a non-eco/epa way so I guess it's kinda a catch-22.  Getting more mpg would seem to reduce the emmissions per mile though but that's not what they measure.
 
In theory the conversion to ULSD will only lower efficiency by 1-2%, not enough to notice.  However, in practical application, I am guessing there is something else going on with the engine tuning to reduce the overall efficiency.  Perhaps the reduced lubricity of the lower sulfur fuel is causing OEMs to run a bit richer?  Not sure, but the fuel itself has 99% of the btu's in the old fuel, so it has to be something else causing the efficiency drop that folks are noticing.
 
ULSD is only a very small piece of the mileage decrease that occurred on diesel engines produced after 1/1/2007. Much more stringent emissions requirements went into effect as well,  with a required 50% reduction in NOx and hydrocarbons and 90% reduction in diesel particulate matter (DPM). These lead to substantial changes in the engine design, including the use of a regeneration cycle  in most engines to burn off DPM and the addition of EGR valves (no more free breathing crankcases). ULSD helps meet the mew emissions requirements by eliminating much of the sulfur at the source, but that's just one piece.

And further reductions will occur in 2010.
 
I recently purchased a 96 holiday rambler 33ft. We have traveled from lower canada, new york,penn.,west virginia, ohio, indiana, kentucky,and tennessee loaded down pulling a 19 ft. boat . I try to stay around 65-68 if i can. Hard to maintain in the mountain states, drops down to 40mph at times. I seem to always get around 6-7 mph reguardless. But i do seem to have a heavy foot at times.
 
We have a 3500 GMC pick up with a golf cart in the box and pull a 32' Jayco travel trailer and we get about 16 MPG according to the on board computer.
 
We just got back from a 7700 mile trip to the Northwest, of which 5500 was pulling the trailer.  Lots of mountain passes and some very high winds at times.  The overall average for the trip was 12.1mpg.  The truck will get between 18 and 20 mpg when not pulling the trailer.  The poorest milage we got was about 9.6 when driving between Boise, ID and Cortez Colorado with a high headwind.  It's kind of hard to figure loaded and unloaded fuel use because I have a 100 gal fuel tank, so each tank full is used loaded and unloaded.  The weight of our whole rig loaded is about 15000 lbs.

I agree that the newer Diesel trucks have very good performance, however their fuel consumption is definitely less than the earlier models.  I have a friend who had an 03 Chevrolet that got consistently better fuel mileage than mine pulling similar loads.

 
Somewhat of comparison - just put on 2000 miles on 2007 Winnebago Voyage 35A - Northern WI, to Columbus OH, North thru MI over Mackinack bridge, back to Green Bay...very windy, seemed like headwind 80% of the time........ first trip in it.. held at 65 on freeway/innerstate, and 55 on all state 2 lanes - on the rolling hills used cruise most of time except when it would drop out on  inclines and then left on "haul/tow" until level road area again (this whole area doesn't have much for terrain... some rolling hills but nothing major).... got 7.4 total... BUT....taking off .5gal/hr for hours that generator was running, got 8.1mpg for total trip...
Now have baseline - hoping for better.... probably shouldn't hold it at 65-66 all the time - even for some of the rolling knolls in the great lakes area.
 
WhiteEagle said:
got 8.1mpg for total trip...
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WOW!  That's great!  I've got 23,500 miles on my unit (same as yours), and I haven't even gotten close to 8 mpg!
 
Guess I didn't have any personal benchmark but have been reading about the 6.5 - 8 range for expectation and experiences of many... glad I held it at speed limit (+1mph) just to get benchmark and see if I could actually be satisfied staying down to that speed..... didn't seem bad and guess i can relax and enjoy after all......
Will likely see if I can build up 3-4mph prior to inclines and maybe let off a little on the crests - can likely stop the drop down much of the time  ... should have mentioned I was not towing anything ....
If the generator estimate of .5 gal/hr running is applicable to my 5500 Onan, the appears I should be satisfied first data in should be representative and believe I can help it do better if and when i think about it.......
 
WhiteEagle said:
Guess I didn't have any personal benchmark but have been reading about the 6.5 - 8 range for expectation and experiences of many... glad I held it at speed limit (+1mph) just to get benchmark and see if I could actually be satisfied staying down to that speed..... didn't seem bad and guess i can relax and enjoy after all......
Will likely see if I can build up 3-4mph prior to inclines and maybe let off a little on the crests - can likely stop the drop down much of the time  ... should have mentioned I was not towing anything ....
If the generator estimate of .5 gal/hr running is applicable to my 5500 Onan, the appears I should be satisfied first data in should be representative and believe I can help it do better if and when i think about it.......
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I believe the generator estimate is OK for an Onan 5500 at half load, which would be around 23 amps.  My experience shows the "average" consumption of my Onan is around 0.3 gal/hour, although I have high efficiency A/C units that only draw around 9 amps per unit.
 
My Excursion has the V10 and I get 7.5 pulling a 31' TT.  When I'm not pulling, I get 14.
 
I was setting at the gas pump gassing up; a man that was gassing his car in the next lane asked me how many MPG I got; on that thing; I said about 28 and never cracked a smile, I was pulling a toad; I assume he was referring to the toad; he sure had a strange look on his face when I told him that. ;D
 
melvonnar said:
I was setting at the gas pump gassing up; a man that was gassing his car in the next lane asked me how many MPG I got; on that thing; I said about 28 and never cracked a smile, I was pulling a toad; I assume he was referring to the toad; he sure had a strange look on his face when I told him that. ;D
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I love it
 
Hi

It's still early days in my 1996 Ford E350 V8 powered Fleetwood Jamboree Searcher, but I get the impression it's doing around 10mpg at freeway speeds of around 55 to 60mph.

I recently fitted a vacuum gauge (I will post how on the Tech Tips page in the future) as I had these in my UK motor homes. Ths quickly taught me to change down on inclines and never use cruise control or overdrive (unless on a long gentle downhill). It's defintely better to shift down on inclines and let the engine rev, rather than slog up the incline with the right foot down to the floor. The transmission would down shift eventually anyway!

I have a feeling that keeping the needle in the gauge's green region has added several more miles per gallon, indeed I think my RV is getting better gas mileage than my 1989 Mercedes Benz 560SL with its honking great V8 motor!

;D
 

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