MPG for new Vegas/Axis models

[belfastboy]

We now have 9000 miles on our 24.1 and the mileage increased a bit after about 7000. It has been more consistent at 10mpg and I try to keep it under 65mph and close to 2000rpm. It also seemed to be quieter in the cab after about 6000 or 7000 miles.....we figured either that or the noise level had deafened us and it just seemed quieter.

[Chance]

Originally Posted by JamieGeek

Well we just put 1000+ miles on our Axis pulling the Escape: High of 9 mpg and low of 7.5 mpg (mountains of PA and MD).

Granted I'm the same data point I was LOL but we now have 8000+ miles on the odo.

Your report in a different thread of as low as 7.5 MPG in PA seemed so low compared to previous data that it was what prompted me to search for other threads on this subject. This thread seems appropriate to resurrect.

Previously you reported just under 9 MPG with generator running and driving faster than most. What is it about PA conditions that affects your fuel economy so adversely? And is the toad the main culprit?

[JamieGeek]

Originally Posted by Chance

Previously you reported just under 9 MPG with generator running and driving faster than most. What is it about PA conditions that affects your fuel economy so adversely? And is the toad the main culprit?

The main culprit I would guess is the toad combined with the hills and the propensity of the cruise control to run the V-10 at 6,000 rpm on even the slightest incline. I even experimented with Tow/Haul on or off to see if Tow/Haul would keep it in a lower gear longer thinking that it might not downshift so much..well that didn't work. Even with Tow/Haul on the cruise would insist on 6,000 rpm to hold speed ascending. Many times the cruise control wasn't merely content with holding speed: by the time we had reached the crest of the hill we'd be doing at least 5 mph over the cruise set point.

Thus if you wish to have higher mileage going through some mountains/hills I'd suggest foregoing the cruise and use your right foot instead.

[roadhog]

We bought our 2015 Axis built on a 2014 chassis used with 12,000 miles. We have put 8000 miles on it. Over 32 fill ups it has averaged 9.519 mpg.

You need to remember that the generator pulls gas from the same tank used for the engine, so true mpg used for travel will an indeterminate amount higher.

Over this past winter I would occasionally run the engine to operating temperature and usually drive around a ten mile or so loop. I would also run the generator for an hour or so as recommended by Cummins. This activity of course would not get optimal mpg.

On our 5244 mile trip from Missouri to Oregon and Washington and back a few weeks ago we averaged 9.687 with a minimum of 7.745 (strong head wind, hot day running both chassis air, and generator continually for air both driving and stopped) to 11.110 (mild tail wind, only occasional chassis air, and little or no generator). We drove mostly 63-64 mph but occasionally a little faster and mostly 55 in Oregon. Great power in the mountains, but you need to be proactive in getting out of cruise control if you don't want to hear the V10 scream. With manual throttle and allowing the speed to drift down a little on the steep hills you can keep it in a little higher gear and keep rpms at a much more pleasant level.

Really like the layout of the 24.1 and it drives beautifully after some chassis upgrades. Mileage is pretty reasonable for the room the Axis has, and love the 55 gallon gas tank (except at the pump of course). Fantastic for pulling into places a bigger coach could not go or park. With truck and trailer you are definitely ready to get out of the truck at the end of the drive. With the Axis, as my wife says, at the end of the drive you are still ready to just stay in it and relax. The little slide out creates an amazing amount of living space in the most needed area.

The only thing that is a concern to me is repair access to the engine.

Hope this helps.

[belfastboy]

Yes, I use the cruise control only on the flats. We run the gen minimally and find the vent blows enough air that only in the mid to high 90 degrees do we run the cab air. We only run the house air occasionally to circulate it or if we are away for the day to knock the temp down to a more reasonable level.

[Beacher]

If you carefully plan your trips to always go downhill in all directions using online trip-planning sites, a good portable GPS specifically for RV's, and elevation maps from the U.S. geological survey you can be assured of achieving 9-10mpg.

My Dodge Hemi, and Ford Excursion barely achieve that kind of mileage, on a good day.

My dad used to own a gas station, and he always used to say that anyone that can afford a motorhome, (back then they only cost $5,000 to $50,000), shouldn't really be concerned with the price of gasoline. They are going to buy it, regardless!

I now live it, (now that motorhomes cost $60,000 to $2,000,000+), and just buy the gasoline as I need it!

[Chance]

Originally Posted by JamieGeek

The main culprit I would guess is the toad combined with the hills and the propensity of the cruise control to run the V-10 at 6,000 rpm on even the slightest incline. I even experimented with Tow/Haul on or off to see if Tow/Haul would keep it in a lower gear longer thinking that it might not downshift so much..well that didn't work. Even with Tow/Haul on the cruise would insist on 6,000 rpm to hold speed ascending. Many times the cruise control wasn't merely content with holding speed: by the time we had reached the crest of the hill we'd be doing at least 5 mph over the cruise set point.

Thus if you wish to have higher mileage going through some mountains/hills I'd suggest foregoing the cruise and use your right foot instead.

I rarely use cruise control on hills for this very reason. Having said that, a jump into the 6,000 RPM range is unexpected -- would have not expected that at all.

At normal cruising speeds a downshift from 5th (Overdrive) to 4th (direct drive) should only bump engine speed to around 3,000 RPMs, which suggests to me that your Axis is downshifting to 3rd gear, or maybe even 2nd gear depending on how fast you were going.

In any case it's not that beneficial to push engine speed to near 6,000 RPMs because the 2-valve engine won't develop that much more power (if any at all) compared to something around 4,000 RPMs in next higher gear.

I'm hoping (based on technology and reviews) that the upcoming 6R140 transmission will avoid some of what you describe. Closer gear spacing near top end should also help, as well as improved manual gear selection.

The new transmission should also reduce cruise RPMs by about 5%, or around 100 RPMs lower (like 1,900 versus 2,000).

[pstandiford]

I'm not sure what transmission I have in my 2016 Chateau 31l but I can tell you that it does not scream at me when I hit a hill like our 2000 Pace Arrow did. Just drops a gear and pulls.

[Chance]

Originally Posted by Beacher

If you carefully plan your trips to always go downhill in all directions using online trip-planning sites, a good portable GPS specifically for RV's, and elevation maps from the U.S. geological survey you can be assured of achieving 9-10mpg.

My Dodge Hemi, and Ford Excursion barely achieve that kind of mileage, on a good day.

My dad used to own a gas station, and he always used to say that anyone that can afford a motorhome, (back then they only cost $5,000 to $50,000), shouldn't really be concerned with the price of gasoline. They are going to buy it, regardless!

I now live it, (now that motorhomes cost $60,000 to $2,000,000+), and just buy the gasoline as I need it!

Perhaps more so for campers than travelers.

If I can drive an Axis-size motorhome that got 12 MPG, it would mean being able to drive 50% farther at the same expense compared to 8 MPG. Gasoline is the highest variable cost for us and exceeds campgrounds and others by far.

There is a lot of difference between those who drive a few hundred miles and then camp all week in one place (my sister and brother-in-law come to mind) versus those who often travel cross country to visit new sites, National Parks, etc...

Over the years I've noticed that on average smaller motorhomes get driven more miles than larger ones. I personally expect fuel economy to be more important to Axis-Vegas buyers if for no other reason than their compact size.

[belfastboy]

I found that in "cruise" mode it would spike to the high 3000's/low 4000's and scream but back off into the mid 3000 range. Still too high as the engine could still maintain 60mph using the pedal and stay in the low 2000 rpm range. I only use the cruise feature to give my foot/ankle a rest during a long day's drive. I prefer to stay as engaged as I can whilst driving, to keep me alert and present. At least the engine "scream" on cruise would jolt me back to reality if I personally went into cruise mode!!!

[belfastboy]

On our trips so far we average 150 miles aday. Usually a travel day will be 400 miles max then we stay put for 3-4 days or do smaller side trips. Our gas costs work out to 25-33% of the cost of our vacations. With park fees about the same and then food/entertainment the final 1/3. Right now with our Canadian dollar being hammered the biggest bite is spending US$. I paid a 35% premium at the bank today and that hurt. But if we throw in the odd night in a Walmart/Cabelas it will all work out.

[Mr Sunshine]

We have about 5000 miles on our 2016-Vegas 25.2, and have averaged 9.5 mpg, pulling a small car. Rarely run over 70 mph on the interstate, and speed limit on the two lane roads. Those miles were from Ohio to Minnesota and Wisconsin, then to Upper Michigan, North Carolina and Florida, and a bunch of states in between. Much better than the 7.5 we got with our 33' gas coach.

[Chance]

Is it likely some Axis-Vegas models came with different final gearing? If so it could explain differences in fuel economy.

Standard gearing would suggest approximately 58 MPH at 2,000 RPM. Does anyone see higher motorhome speed at 2,000 RPM in top gear?


I recall a video interview of Thor manager stating that RUVs had taller gearing which allowed them to cruise at 2,000 RPM and get 12 MPG. Perhaps Ford offers gearing options under special orders.

[belfastboy]

We are off on a trip leaving Saturday. Will pay closer attention to it but my recall is that we can cruise at 62mph and still be at the 2000rpm. But have never gotten more than 11 mpg on a tank, flat land, no wind.

[groswald]

Drag is directly proportional to speed.

For that reason, driving habits are the single largest contributor to mileage in a motorhome. This is followed closely by weight. Terrain also contributes, but to a lesser extent since you usually go down as much as you go up.

I get 9+ MPG in our Axis, but I rarely drive above 65 and average about 60 on the interstate. We tow a lightweight trailer with our Spyder for a GVW of 14,500-ish (if I remember right).

Maintain 65 instead of 60 and I'm sure the MPG would be below 9.

In a bus it pays to not be in a hurry!

Randy

[Chance]

Originally Posted by groswald

Drag is directly proportional to speed.

For that reason, driving habits are the single largest contributor to mileage in a motorhome. This is followed closely by weight. Terrain also contributes, but to a lesser extent since you usually go down as much as you go up.

I get 9+ MPG in our Axis, but I rarely drive above 65 and average about 60 on the interstate. We tow a lightweight trailer with our Spyder for a GVW of 14,500-ish (if I remember right).

Maintain 65 instead of 60 and I'm sure the MPG would be below 9.

In a bus it pays to not be in a hurry!

Randy

Not being in a hurry can indeed save a lot of fuel. Unfortunately, those of us not in as big a hurry could save even more fuel if willing/able to downsize engine commensurate with lower speed requirements.

The amount of required horsepower between driving at 60 and 75 MPH on flats without wind is huge.

Since these engines are sized to cruise at 75 MPH or higher, climb hills at relatively fast speeds, and have excess power for acceleration, what happens is that as we drive slower the engine becomes less efficient which essentially offsets some of the otherwise possible gains.

I found 2010 Ford V10 industrial engine data which shows that these engines are sized larger than what should be considered optimum for small motorhomes (from fuel efficiency standpoint). More power is always nice but often comes at expense of lower fuel efficiency. You may find this Ford technical data interesting.

[davidgebo]

We averaged 8.5-9 mpg in the Smokies pulling our convertible behind us. We averaged 60-75 mph most of the trip with some stop and go, and rural, windy country roads as well. We have 8,000 miles on the odo. Installed Safe-T-Plus for steering comfort and tire blowout control. Also had the front end re-aligned before we installed the steering stabilizer. If you don't think you need the Safe-T-Plus unit, fine. But I am telling you, the difference in handling is AMAZING. I would not have believed a stabilizer could make such a difference in ease of driving. Easy to install, but the fine adjustments can take some time. The unit for the Vegas is about 330.00, and installation is about 2 hours shop time with the adjustments which take more time than the install. Shop around Ionline for the Safe-T-Plus. I found prices ranging from 330.00 to 475.00 for the unit. I also use a Sani-con macerator sewage pump for convenience and a smaller waste hose. Plus, the hose I have expands to 30 feet, so I have more flexibility parking the coach on the campsite.

[Chance]

Anyone observe speed at 2,000 RPM? Is it higher than 58 MPH?

I'm interested to what degree they could be modified.

[erikdjensen]

We have a 2016 25.2 Vegas(26 feet). We have had it for a couple of months and have about 3K miles on it. We are getting around 10 mpg the last couple of fill ups.

[erikdjensen]

Originally Posted by Chance

Anyone observe speed at 2,000 RPM? Is it higher than 58 MPH?

I'm interested to what degree they could be modified.

Taking ours to the shop for some work next Saturday - about 100 miles away in Portland. I will test out the 2,000 RPM then. I have noticed the speedometer is a little slower than what my GPS says my speed is.