Disappointing gas mileage

I'm sure this topic has been discussed at length, but just feel frustrated.  We traded a 30 foot class A for our PC and hoped we would gain at least a little better gas mileage.  Both vehicles have the same Ford e350.  Our class A often got 9 mpgs towing our Ford Escape.  We typically don't go over 65 and are mindful of weight loads.  Have now driven our PC in various conditions, towing and not towing.  Our best mileage todate is 8.5 mpg.  How is it that the same motor on a smaller, more aerodynamic vehicle can't beat a 30 foot long shoebox driven much the same but with a heavier load? Very disappointing.

Every once in a while I will read a post like yours.  I can't explain why a few people get poor mileage.  The only thing I can suggest is to do what you can with driving habits and vehicle maintenance to see if you can influence it for the better.

Do keep in-mind that some people will claim great gas mileage.  I for example could say that our rig gets between 13 & 14 mpg on the open road.  Though true in one sense, it would be very misleading to proclaim.  If we travel on a level interstate highway with no winds and nobody near us (mainly night driving) at a steady 55 mph, our ScanGauge-II will be reading about those figures.  But keeping track of miles driven and gallons of fuel purchased throughout the duration of a vacation, we calculate trip averages of 9.5 mpg when towing our Jeep Liberty, and 10.5 mpg when not.  Also remember that we live in the Chicago area so much of our driving is done in the Great Plains where better mileage is achieved.

One other influence is generator usage.  Because it uses the fuel from the main fuel tank, the more you run the generator, the lower your gas mileage will calculate.

Oh yes, if your rig is built on an E450, most people seem to drop about 1 mpg due to the change in gear ratio in the rear axle differential.

Thanks Ron.  Can always count on you to help out on the forum. I guess maintenance means filters and oil, etc. We just changed the oil and only ran the genie for 20 - 30 minutes for maintenance. Husband says he hasn't checked the air filter, so will do that before leaving for Acadia NP this coming Sunday.  I'm guessing with traffic congestion up the east coast things will not improve. We do have the e350 with a slide.  Any other thoughts will be appreciated.
Rose & Earl

I guess maintenance means filters and oil, etc. We just changed the oil and only ran the genie for 20 - 30 minutes for maintenance. Husband says he hasn't checked the air filter, so will do that before leaving for Acadia NP this coming Sunday.  I'm guessing with traffic congestion up the east coast things will not improve. We do have the e350 with a slide.  Any other thoughts will be appreciated.
Rose & Earl

You are very welcome!

Yep, oil & filters, proper tire inflation, etc.

I have been using 5W-20 full synthetic motor oil since the second oil change.  Around here where we live, Quaker State full synthetic can be purchased occasionally on sale with a rebate for $1.99 per quart at Menards.  That brings the cost down to regular oil.  I would like to think that full synthetic oil helps a little in fuel economy, but I can't say for certain.  It does provide me with a little more peace of mind when engine braking in the mountains, watching the tachometer get near that red mark.

Full synthetic gear oil is available for the rear axle differential.  That too might help mpg a bit.  I would not change that oil until it's time, but am planning to use full synthetic then.

I do wonder if all the mounted RV accessories, roof storage, and things some people hang on their rigs, has a measurable influence on fuel economy.  General "weight" is always a factor too.  Don't bring along heavy things that you find yourself never using......but keep the spare tire and jack. 

Rose and Earl

Ron presents some very good points.

We had a 2008 2350 with slide on an E350 chassis and over the first 10,000 miles of usage we averaged 9.98 miles per gallon.

Some of the things we found that help the mileage:

1.  Maintain good tire pressure.  Good is hard to define.  The tires need to be inflated enough to carry the load but not so much as to cause a rough ride and excessive tire wear.

2.  A clean air filter helps .  I added a K&N air filter primarily to increase time between filter changes.

3.   Starting and stopping  in heavy traffic or at stop lights destroys the mileage. 

4.  When towing I usually maintain about 60-62 MPH.

5.  Hills will also greatly affect mileage.  I found that if I am able to keep my speed in the 60+ range I can climb a lot of hills without having the transmission down shift.

On a separate issue the Ford V10 used in some if not all Class A's is slightly different than the V10 used in an E350 Class C.  The Class A would have a 3 valve configuration and the Class C would have a 2 value.  I do not know if this was the case in your previous Class A.

Barry

Thanks Barry Sue.  I think Earl will replace the air filter before we head out.  Always try to watch our speed. Sure would be nice to get 10 mpg, even 9

BuffaloRose

I am posting my log file so that you can see the MPG we were maintaining over the past few years.  We have a 2008 PC2350 with a ladder, luggage rack and solar panel mounted. We also travel with a Stowway box on the hitch.

The trip mileages reflect both back roads and highway driving.

Bill G

I failed to mention ...it is an Excel File.

Got it Bill.  You have meticulous records there.  Thanks for sharing.  At a glance  there have been times you got some great mpg.  Outstanding! We generally only check our mileage occasionally at the beginning of purchase of a new/different unit to get an idea of how we are doing.  We have only filled the PC 4 times since purchasing in February. My husband was saying maybe we should start keeping a log (that means me ).  I'm beginning to think "why worry, we love our PC and traveling to new places no matter what the mileage." I think we will just be cognizant of things we can manage as noted by you folks and then enjoy the trips!
Thanks again. 
Rose and Earl

Keeping Logs goes with the fact that I had to do it  everyday for 38 years as a truck driver.  And, it allows me to go back over the records to see the overall performance of my PC. 

I will add that at the beginning the mileage was between  8 to 9 mpg. on the first trip from Mass. To Florida.  After we had a front end alignment, and engine timing adjusted we were able to improve the mpg .  The maiden voyage just after delivery from the factory.

Bill G.    . 

Old habits can be good habits as your records indicate .  We just had a front end alignment so only about 30 miles driven on this tank after having that done.  Plan to change air filter prior to leaving for Acadia NP on Sunday. Might look at timing adjustment when we return.  Good info.  Maybe some tweaking will help a bit.
Thanks,
Rose & Earl

Perfect timing for Acadia NP .....Great foliage and no crowds

 

I use the Android app called Fuelio to keep track of the mileage on our 2 vehicles. Works great. Don't know if there is an Iphone version

Good topic,,, so of course have to add my 2cents haha

    First,,, I try and maintain the Beast to good standards,, do not worry to much unless the MPG goes crazy,,    Usually in the 9..... range,,, do know that wind is big booger also

   Question,, especially for some of you guys that do tons of records.   

    Most of us buy the cheapest gas we can find,,, I am a big Flying J fan..... I do know that the cheaper brands of gas do not have the same additives/detergents in them from the more expensive brands,, Shell/Texaco  etc,,,,,   I do a fill up about every 4/5 time with better brand gas or add some additives to the tank......... could buying the cheaper gas make a difference.???      Since it would be cheaper to buy the additives over 10 to 15 cents a gallon,,,, just curious

sparky

Sparky, You bring up a very good topic.  Does the brand and octane of gas influence fuel economy?  I have an opinion, but will wait a bit before sharing it.