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I now have 5,000 plus miles and have never been over15.5 MPG. Took it in and found nothing. Only asked if I use Premium which I have from the start. I carry at least 1,000 lbs of tools and never am on the highway. All my work is within 10 miles of my home. The shift points seem to hold on to long so some times I force it to go to a higher gear. Not happy since it was a reason i sold my 1 ton NV3500 for the 11MPH it gave me. I also seems to surge when you ease on the gas from a start or rolling away from a stop. I have to watch it or my tools wind up on the floor.
They report , every extra 100lbs of weight decrease fuel economy by 1%(including people tools etc)
 
I now have 5,000 plus miles and have never been over15.5 MPG. Took it in and found nothing. Only asked if I use Premium which I have from the start. I carry at least 1,000 lbs of tools and never am on the highway. All my work is within 10 miles of my home. The shift points seem to hold on to long so some times I force it to go to a higher gear. Not happy since it was a reason i sold my 1 ton NV3500 for the 11MPH it gave me. I also seems to surge when you ease on the gas from a start or rolling away from a stop. I have to watch it or my tools wind up on the floor.
I average 26-27 mpg over a mix of urban and freeway. With Cargo Van on E and windsurfing gear in the back. Gear is probably 150 pounds or so.
 
I now have 5,000 plus miles and have never been over15.5 MPG. Took it in and found nothing. Only asked if I use Premium which I have from the start. I carry at least 1,000 lbs of tools and never am on the highway. All my work is within 10 miles of my home. The shift points seem to hold on to long so some times I force it to go to a higher gear. Not happy since it was a reason i sold my 1 ton NV3500 for the 11MPH it gave me. I also seems to surge when you ease on the gas from a start or rolling away from a stop. I have to watch it or my tools wind up on the floor.
My best mileage was on a 3019 mile trip in the desert West last Spring - moderate speeds and very low traffic density: 28.1 miles/gallon.
 
I now have 5,000 plus miles and have never been over15.5 MPG. Took it in and found nothing. Only asked if I use Premium which I have from the start. I carry at least 1,000 lbs of tools and never am on the highway. All my work is within 10 miles of my home. The shift points seem to hold on to long so some times I force it to go to a higher gear. Not happy since it was a reason i sold my 1 ton NV3500 for the 11MPH it gave me. I also seems to surge when you ease on the gas from a start or rolling away from a stop. I have to watch it or my tools wind up on the floor.
I have a 2021 Weekender with a pop top. After 10,000 miles I consistently get 23.5 on highway trips with lots of up and down mountains - loaded down and about 12.5 in the city with just the kids. The user's manual refers to C/S/E modes but mine was always in C (comfort) mode.

I think someone on this site (nobody at the dealership could) informed me that Mercedes switched to "C" mode only with the 9 seed transmissions on these models. Later on, someone at Peacevans commented that this may be a blessing in disguise because the battery charging algorithms were different in the different modes and people were inadvertently ending up with discharged auxiliary batteries when they forgot to switch to the correct charging mode.

I have come to really respect Mercedes design of this transmission and have accepted the poor city mileage. The car has plenty of pep off of the line and immediate downshifting when lane changing, etc. I would say it works flawlessly at any speed. The shift points are not noticeable and I use the paddle shifters for downshifting frequently on the long declines after mountain passes. Just my two cents!
 
I now have 5,000 plus miles and have never been over15.5 MPG. Took it in and found nothing. Only asked if I use Premium which I have from the start. I carry at least 1,000 lbs of tools and never am on the highway. All my work is within 10 miles of my home. The shift points seem to hold on to long so some times I force it to go to a higher gear. Not happy since it was a reason i sold my 1 ton NV3500 for the 11MPH it gave me. I also seems to surge when you ease on the gas from a start or rolling away from a stop. I have to watch it or my tools wind up on the floor.
Based on my experience with my 2020 126" cargo van using it pretty much within a 10 mile radius of home -- but just for an errand running vehicle and carrying no cargo/tools my van averages around 22mpg running 91 sometimes ethanol free and sometimes with 10% ethanol. (Van engine seems to not care which type of 91 I put in the tank.)

I think the 15.5mpg your van delivers is normal. The stop/start usage I assume you subject the van to and extra 1000lbs really hammers gas mileage.

Might mention my 2020 van has no auto engine stop/start feature.

All I can offer is be sure the van tires are properly inflated for the load you are carrying and try to mind how you drive. Often vehicles used in a business are driven rather hard as the driver is on the clock so to speak and wants to get from point A to B and on to C and so on ASAP. While the vehicle is driven in a law abiding manner (mostly) it is driven hard. As a consequence gas mileage suffers.

The van engine is pretty precisely fueled and monitored for same -- my experience over the years is this is typical of turbocharged (or supercharged) engines -- so if it was running "rich" the dash would be lit up like a Christmas tree.

A bit of a warning. Do not let the engine air filter go too long. You may have only driven the van 5K miles but working as hard as it appears to have been working means the engine is consuming besides lots more fuel lots more air.

I let the air filter go too long on 2 cars. (With one car I was distracted with caring for my elderly parents and just lost track of time. The second car was a (factory) supercharged car and I was at fault for not more carefully reading the service schedule and I let the filter go approx. 7K miles beyond the miles at which it should have been replaced.)

In both cases after installing a new air filter the engine ran better. Really underlined the importance of changing the filter on time.

So be proactive with the engine air filter servicing. Don't let it go too long and in fact I'd be inclined if I were you to change it early.
 
1000 lbs of gear+never getting on the freeway+ never more 10 miles from home = 15.5 mpg. You are probably never even properly warming the van up. Your van probably never warms up enough to get into closed loop. It is constantly running in warm up mode with 1000 lbs of cargo.
While I haven't bothered to confirm this with my van based on having confirmed when the engine controller goes closed loop with other engines the van engine controller is in closed loop mode shortly after engine start. With other engines this was when the cold engine high idle speed dropped to near normal (and with engines equipped with a secondary air injection system when I heard the air injection pump shut off). This RPM drop doesn't take but a few moments or so. My SOP is to wait after cold engine start until the idle speed drops before puling away.

Also, I have done a bit of data logging of my van's OBD2 data. Coolant temperature gets to normal operating temperature (approx 200F) in under 10 minutes. It takes me around 15 minutes to drive the 5+ miles from my place to my usual destinations which are with few exceptions within around a 5 mile radius of my place.

So the van engine gets up to temperature. And being 5+ miles and 15 minutes from home I have to drive the 5+ miles to get back home which has the engine running for another 15 minutes or so.

Sure oil temperature lags coolant temperature but given I drive the 5+ miles and 15 minutes to some destination and back home again the oil is up to temperature, too.

I do admit I occasionally (roughly every couple of weeks) take the van on a longer drive and on the freeway. Anywhere from 20 miles to nearly 70 miles (round trip and including the 10 miles I have to drive to get to the freeway then back home again after leaving the freeway). Not so much because of any concern the engine doesn't get warm enough from my day to day usage of the van but to sort of clear out any "cobwebs" from the engine. But the engine appears to be pretty clean running. It never manifests any signs of any benefit from the longer drives.

I would have to believe the OP given his usage of his van and with the 1000lbs of extra weight it is hauling the engine gets up to operating temperature.
 
I don't really think it is the 1000 lb load, it is the startup and stop & go, probably a good number of stop lights and/or 4-way stops with some amount of expediency getting back up to speed.

I think I get around 15 - 16 around town with a heavy utility trailer loaded with 500-1000 lbs of cargo ... or like 1 yard of top soil.

My van easily sits around with an extra few hundred pounds of panels, and routine tools; and a square roof bar. Had to make a trip out towards the mountains today, to check on a property, do some quick maintenance, take some photos & measurements for some upcoming weatherization. Chucked a few extra things in the van, a few extra tool cases, a ladder or two, lawn mower, weed whacker, leaf blower, ... I did take some bags of mortar out, figured I didn't need to haul those. LOL.

Outside of rush hour, and I wasn't in a rush ... I know the route well. Rural highways with a few traffic lights and villages / towns, a couple steep hills to climb, ...

Just got back:

Image


It blipped 31.5 a couple times, slowing down mid way in the return, but I knew that wasn't going to be attainable. The computer goes something like 29.7 30.1 30.3 30.7 31.1 31.5 ( with the lit/100km conversion our vans do ) and this new best trip translates to 7.5 lit / 100 km. Which is about what my old 1.8 liter VW Polo / Golf / ... engine did back in the day.

Pretty solid.

Anyway, I hope there's some constant speed interstate or rural highway trips in OPs future, so he can experience some better mpg numbers. Go for a little drive into the country side on a Sunday morning :)

Also make sure your tire inflation is good all the way around, ... I know I need to check mine.
 
A couple short trip data points.

With 20.5 mpg on the dial; picked up about ~2500 lbs of cargo. 10min mixed trip ( local road, interstate on/off, lights, local road ) bit of up hill and getting up to interstate speed, a bit of coasting down and slowing for the interstate exit, 20 mpg, then half a mile up hill ... arrived with 18mpg

Super short trip. In town only. Rush hour. Traffic lights. Eco OFF. Trailer with a ditch witch on it. 2 miles. 15 min stop and go. Part up hill. Average speed 15mph. 11.5 mpg.

Probably not bad, all things considered, versus the typical pickup truck.

But yeah, rush hour, stop and go, not benefitting from getting up to speed and coasting down ... hard to get the mpg.
 
Discussion starter · #29 ·
I now have 5,000 plus miles and have never been over15.5 MPG. Took it in and found nothing. Only asked if I use Premium which I have from the start. I carry at least 1,000 lbs of tools and never am on the highway. All my work is within 10 miles of my home. The shift points seem to hold on to long so some times I force it to go to a higher gear. Not happy since it was a reason i sold my 1 ton NV3500 for the 11MPH it gave me. I also seems to surge when you ease on the gas from a start or rolling away from a stop. I have to watch it or my tools wind up on the floor.
I now have 6,200 miles and have resorted to hitting the upshift as much as possible and try not to idle much. Hit 17.7MPG at best so far.
 
One thing you can do to validate the accuracy of the gauge is to go old school and calculate based on your fuel pump numbers and odometer.

I've always been skeptical mine is accurate...but I don't bother with the accounting.
 
I am using a Real-cost method for tax purposes so I record every mile driven, every mile driven for business purposes, every drop of fuel purchased, and every penny spent so that I can figure out exactly how much I spent, what percentage is deductible, claim the full legal amount and present all relevant records to the IRS if they ever happen to ask for them.

I also record fuel economy because once I have all that other math programmed in, it only takes a few more formulas to calculate mpg exactly per tank, roughly per month, and roughly per year. Funnily enough my change in driving habits occurred practically with my last service; I have about 12.5k into it since with a computer calculated mpg of 29.6. Over the same period I have roughly averaged 27.6 mpg based on miles/gallons.

That suggests an error of 2 mpg optimistic, or 7.2%ish. I’d call that pretty substantial.
 
I am using a Real-cost method for tax purposes so I record every mile driven, every mile driven for business purposes, every drop of fuel purchased, and every penny spent so that I can figure out exactly how much I spent, what percentage is deductible, claim the full legal amount and present all relevant records to the IRS if they ever happen to ask for them.

I also record fuel economy because once I have all that other math programmed in, it only takes a few more formulas to calculate mpg exactly per tank, roughly per month, and roughly per year. Funnily enough my change in driving habits occurred practically with my last service; I have about 12.5k into it since with a computer calculated mpg of 29.6. Over the same period I have roughly averaged 27.6 mpg based on miles/gallons.

That suggests an error of 2 mpg optimistic, or 7.2%ish. I’d call that pretty substantial.
Been a long time since I have had to log miles for business use of a vehicle. And this was before the on-board computer showed up.

With my more modern vehicles I compared both the on-board computer fuel consumption and my by hand calculations. While they weren't identical they were close enough, and the on-board computer numbers consistent enough, for comparing mileage fill up to fill up. Since I didn't need to satisfy the IRS with my numbers I decided to just rely upon the on-board computer's numbers.

I'll compute fuel consumption manually a few fill ups just to see how close -- or not -- the results of the two methods are.
 
Seeing recent life on this thread, I'll report that my trip computer (2020 cargo) is always somewhat optimistic vs. actual miles & gallons calculations. Varies from within .5 MPG up to 2-3 mpg high, like it will show 28.5 at fill-up and the math will show something like 26. Or it will show 26.3 and the math will show 25.2, and so on.
That said I am getting at least a few MPG on average above the USA EPA rating of 20/24, most of the time. Where I live it's mostly rural-ish roads and strip-town driving, otherwise highway or freeway. Not stop-go big city traffic. So far I have only used the [C] setting. I will try the [E] setting at some point for a stretch of time and see what I get.

My take on OP's situation is that the 1000 lbs. load is a significant factor when combined with constant stop-go driving. 1000 lbs. is ~25% of empty vehicle weight - not trivial. Now, once that 1000 lbs. is up to speed, relatively little extra energy is needed to keep it at that speed (a body in motion, etc.). But having to accelerate that 1000 lbs. from zero to 20-25 mph over and over again in short bursts is going to use a fair bit more energy (a body at rest, etc.). Possibly enough to account for that low MPG. Bringing it up to speed more gradually will help a bit, which seems to be what was reported, e.g. ~17 vs. ~15.5.
 
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