Forester MBS Fuel Consumption

[Aspenmeadow]

Well, that is interesting. The sound is not bad a about 50, but becomes a low roar at 60. It might be road noise because the roads in Washington and Oregon are really deteriorating fast. So, it could be just that simple.

Keithe, did you get that milage when it was new?

I do apologize for getting off the subject.

[Keithe]

We started out at about 11 mpg when we drove the RV from Ohio to Oregon but we also encountered high winds in the trip. Since then, our mph has steadily increased. Our last two trips where constantly over 15 mpg.


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[Pod2Vibe]

While never being anywhere near loud as noted above, the Sumo's really made it quiet and smooth.

[MNtraveler]

Here are the mileage stats from our just completed 2440 mile round trip from the Twin Cities, MN through WI, IL and MI to Ontario, up around the Great Lakes staying on the Canadian side, through Thunder Bay and back down the MN North Shore to the Twin Cities.

Here is the data:

Date Odometer Miles Fuel MPG
Start 1804
6/12 2052 248 18.94 13.1
6/13 2339 287 11.586 [not full, combined]
6/15 2445 106 14.474 15.1
6/15 2622 177 12.399 14.3
6/19 2827 205 13.264 15.5
6/19 2973 146 10.061 14.5
6/21 3195 222 15.068 14.7
6/22 3339 144 10.451 13.8
6/24 3534 195 13.424 14.5
6/25 3706 172 11.931 14.4
6/27 3879 173 11.875 14.6
6/28 4079 200 12.943 15.5
TOTAL 2275 156.416 14.5

In case that doesn't format too well, a screen shot is attached. The MBS performed admirably and is a real trooper on hills both up and down! The MPG data include flat areas, mountain climbing, strong head and side winds and both hot and cold weather. The lack of variability is surprising. The lower first day may be due to starting with city driving. We ended with city rush hour driving too, but haven't refueled yet so that does not show here.

[ShermanD]

Originally Posted by Beachsailor

Has anyone compared the Trekker cab verse the sleeper cab for difference in drag?

We have a 2017 MBS 2400WS with the trekker cap. Only have about 1100 miles on it so far but we averaged just over 13 mpg on an 800 mile trip to the UPPER and back, Most of the mileage was on I-75 running 65 to 70. We are real happy about the mileage because that was while pulling our loaded enclosed motorcycle transport trailer which weighs in at 3000 pounds loaded.

We are heading north again on Friday, My step-sister invited us up to her place in Cross Village. Hope its a nice weekend because we plan on riding the "Tunnel of Trees'. I will report back on the mileage for this trip when we get back.

[bob5560g]

Thanks for the info. What was your usual cruising speed on the interstate?

I'm getting 1 mpg less at around 13.5 at 65 mph. Here's some extreme data. Speed limit across west Texas is 80 which gave me 9.8 mpg. So as a test I slowed down to 55 for the next tank and got 15.0. I think the wind resistance at the higher speeds is a mileage killer.....

[MNtraveler]

Originally Posted by bob5560g

Thanks for the info. What was your usual cruising speed on the interstate?

I'm getting 1 mpg less at around 13.5 at 65 mph. Here's some extreme data. Speed limit across west Texas is 80 which gave me 9.8 mpg. So as a test I slowed down to 55 for the next tank and got 15.0. I think the wind resistance at the higher speeds is a mileage killer.....

If that question was directed to me, we were usually traveling at 55, probably averaging more like 50 overall. Lots of construction starts and stops. Very rarely did we get up to 65 and the wind resistance is quite significant. The max. speed across Canada is 100 kmh which is roughly 60 mph. But they have you stop for construction every 10 miles or so! LOL

[ShermanD]

Originally Posted by bob5560g

Thanks for the info. What was your usual cruising speed on the interstate?

I'm getting 1 mpg less at around 13.5 at 65 mph. Here's some extreme data. Speed limit across west Texas is 80 which gave me 9.8 mpg. So as a test I slowed down to 55 for the next tank and got 15.0. I think the wind resistance at the higher speeds is a mileage killer.....

My step-brother is an engineer working R&D for GMC. We got to talking about the 3 liter V6 Turbocharged diesel engine along with the 5 speed auto that Mercedes-Benz uses on their Sprinter 3500 chassis.

Diesel engines are designed to provide the best pulling power along with fuel economy when within the maximum Torque range. That combination is between 1400 and 2400 rpm. At 2400 RPM which is at the top of the torque range our Sunseeker cruises at a cool 60 MPH.

As the rpm's go up that torque goes down BUT the Horsepower increases. It takes calories (fuel) to produce Horsepower. At 70 mph we are turning 2800 RPM which would obviously burn more fuel, running 80 mph would use even more.

Obviously you would be loading down the engine if you try to run in fifth gear at 1400 rpm so you would want to be in the 2000 to 2400 rpm range when running in fifth gear which would equate to optimum fuel economy running down a level, at sea level road, with no head wind in the 50-60 mph range.

Basically if you are into pinching pennies and don't mind being run over by semis, then running 50 down the expressway would be the thing to do. Here in Michigan the truck speed on the interstate is 60 mph and most run 65. I choose to run with them and not worry about the gallon or two a mile I may lose instead of being run over by them.

[MNtraveler]

The engine works remarkably well and the cruise control does a commendable job keeping it purring in the 2000-2400 range for the most part. If it lags, you can kick it down with the gas pedal or manually downshift and it stays in cruise control. Rarely did it have to climb to 3000 either up or down hill but in occasion it did. Clearly it loves to cruise on level to downhill at 50-55 and barely sips fuel at that speed with no incline.

The cruise control is amazing and will be the subject of a future post all of its own!


Land of 10,000 Lakes
2016 Forester MBS 2401R

[HappyHikeRs]

We just filled up for the first time since leaving campground near dealer. Filled up on way home, took 2 short weekend trips and did some driving around town (to acclimate cat to MH). 2401R w/trekker cap - 240 miles, no wind, no toad, flat roads, mostly 60 mph = 15.5 mpg. Hopefully it will improve slightly with break-in and longer trips because I'm getting my car set up for toad duty soon and will head for the mountains, which will surely bring it down some.

[ShermanD]

Originally Posted by HappyHikeRs

We just filled up for the first time since leaving campground near dealer. Filled up on way home, took 2 short weekend trips and did some driving around town (to acclimate cat to MH). 2401R w/trekker cap - 240 miles, no wind, no toad, flat roads, mostly 60 mph = 15.5 mpg. Hopefully it will improve slightly with break-in and longer trips because I'm getting my car set up for toad duty soon and will head for the mountains, which will surely bring it down some.

We got home from our second four day trip on Monday. I just got around to calculating our mileage. Except for the first 80 miles, which was bring the Sunseeker home for the first time, the motor home has been set up for traveling. This includes food, clothing, camping accessories, 1/3 tank fresh water, 1/3 tank black water and towing a 3000 pound tandem axle trailer.

Over the course of 1400 miles, we have averaged just over 14 mpg. This includes our last northbound trip in which we encountered a 30 MPH headwind the entire way. The mileage for that 250 mile portion was about 10 mpg. On the highway I will run 65 mph with the cruise on whenever I feel comfortable doing so.

Whenever we travel, we will have the tag in tow so I will never be able to provide that 16 mpg that I am quite sure the MB Sprinter diesel is capable of. To get that kind of mileage INMO it will take not exceeding 60 mph, without using the cruise, and anticipating hill climbs by slowly accelerating prior to the climb and then slowing as necessary to keep from downshifting if possible. If a person is capable of always keeping the engine speed within the 1400-2400 rpm torque range, they will get the best mileage.

Although the Cruise Control is probably the best I have used, it does have its downsides that cost fuel mileage. First off it can't anticipate a hill and speed up prior to the climb, then it uses the engine braking capabilities on the downside of that hill to keep the vehicle within the set speed parameters, instead of using the vehicle weight to let you freewheel down the hill and thus gaining distance using very less fuel.

[LoveLife7478]

Just finished about a 300 mile round trip and averaged just over 14 MPG, not towing anything. Ran between 55-65 MPH mostly about 60 though. All flat roads and not much wind.

[Philrisl]

Currently traveling with my new to me 2015 Solera. Although I didn't weigh it I am sure I am near gross weight. Also towing a open trailer with an 800 pound Harley. On the flat roads of Florida and Georgia at 60-65 mph we got 14 mpg. In the mountains of the Carolinas we got about 13.2.

[namusmc]

I was just wondering if anyone has run out of fuel and their experience getting on the road again. I just had the near experience of running dry with a blinking low fuel indicator light.

[ShermanD]

Originally Posted by namusmc

I was just wondering if anyone has run out of fuel and their experience getting on the road again. I just had the near experience of running dry with a blinking low fuel indicator light.

What do you mean by "near experience"?

How many gallons of fuel did it take to fill your tank?

The manual states that the MB Sprinter based motor home fuel tank holds approximately 26.4 gallons and the low fuel light is set to go on when there is just over 5 gallons of fuel left. Even at 10 mpg, which is most likely worst case scenario, you would still have close to a 50 mile safe zone.

The time my low fuel light went on, I stopped at the next station, approximately 5 miles later and it took just over 19 gallons to fill the tank. From what I have read here, the general consensus is the low fuel light seems to go on at around the 19 gallon mark.

Remember to check your DEF tank level on a regular basis. Although it is supposed to last approximately 2000 miles, DEF can be had much cheaper when purchasing it at a truck stop DEF pump. Run out of DEF and you will be driving at a snails pace.

The MBS owners manual is really worth reading. Maybe not in its entirety, but at least the important parts, like tire pressure, maintenance schedule, tire change procedure, low fuel warning, fluid capacities and how to check them, etc. and probably the most important.

What to do if you run the fuel system DRY.

The fuel tank has been run dry.
X Refuel the vehicle.
If you drive until the fuel tank is completely empty, air may get into the
fuel system. If the engine does not start after refueling, bleed the fuel
system as follows:
X Turn the key to position 2 in the ignition for approximately
10 seconds.
X Start the engine continuously for a maximum of 60 seconds.
If the engine does not start:
X Wait approximately 2 minutes.
X Restart the engine continuously for a maximum of 60 seconds.
X If the engine still fails to start, do not continue trying to start it.
X Consult a qualified specialist workshop.

Here is what happens when you attempt to start the Sprinter after the DEF light goes on

Three short warning tones also sound.
After the message appears for the first time, the remaining DEF supply
will last for approximately 1200 miles (1900 km). The engine can then
only be started another 16 times.
The number of remaining engine starts xx (16 to 0) is shown in the
message every time the engine is started.


It is really amazing all the information that Mercedes Benz felt was important. What is even more amazing is how few new vehicle owners ever take the time to read that important information.

[Santos1060]

Perhaps a new thread is in order, but I've got almost 4,000 miles on my W so far and the DEF light hasn't even come on. The gauge shows that I'm about 1/2 full. Curious if that's the same for others because it contradicts the previous post above about it lasting only 2,000 miles?

[Aspenmeadow]

I now have about 3000 miles on mine with no warnings of DEF. I filled this weekend and it took about a quart and a half.

I am new to Diesel engine operations and DEF was unheard of before I bought this rig. I think it does warrant a separate thread. It is unrelated to fuel consumption and I would guess many know nothing about this additive.

Who wants to start one?

[kysunseekermbs]

Originally Posted by Aspenmeadow

I now have about 3000 miles on mine with no warnings of DEF. I filled this weekend and it took about a quart and a half.



I am new to Diesel engine operations and DEF was unheard of before I bought this rig. I think it does warrant a separate thread. It is unrelated to fuel consumption and I would guess many know nothing about this additive.



Who wants to start one?

Def- Mine def light just went off for the first time at exactly 8000 miles.

Gas mpg - averaging 13.9 on my drive from KY to Arizona so far, I am happy with that because it's been windy and I have avg 75 miles per hour.


2016 Sunseeker W MBS

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[MNtraveler]

Originally Posted by Santos1060

Perhaps a new thread is in order, but I've got almost 4,000 miles on my W so far and the DEF light hasn't even come on. The gauge shows that I'm about 1/2 full. Curious if that's the same for others because it contradicts the previous post above about it lasting only 2,000 miles?

What gauge is that, please?

[MNtraveler]

Originally Posted by Aspenmeadow

I now have about 3000 miles on mine with no warnings of DEF. I filled this weekend and it took about a quart and a half.

I am new to Diesel engine operations and DEF was unheard of before I bought this rig. I think it does warrant a separate thread. It is unrelated to fuel consumption and I would guess many know nothing about this additive.

Who wants to start one?

There is a lot already on these forums about DEF - I would suggest going to the motorhomes general page and search "DEF" for the threads.