[rob99rt]

First of all, we do live in WV so there are some hills around here, so I expect *some* decrease from the 19 mpg highway estimate. However, I'm getting a hand-calculated 13.7-14.2 around here most of the time with an 80/20 split of highway/city, respectively.

Van has 35,500 miles on it and the only thing that's not stock is the tires... currently running 225/75/16's instead of the 235/65/16's, so it's a 4% increase in tire size... that only equates to around 85 rpm at 70 mph, so it's not much. I had to change them out after we'd had the van less than 2 weeks because the stock tires started showing cords and throwing chunks of rubber off of them at 34,500 miles.

Anyway, I talked to a guy from church today who has basically the exact same van as us with the same amount of people to haul (and drives the same route to get home), and he's getting 17-17.5 average, so around 20% better mileage. I have no idea what's going on with this thing.. There's no CEL showing, so it doesn't appear to be something so big the computer is fussing about it, but I can't imagine that mileage being anywhere near normal. If I keep it at 45 mph around here on the side-roads I can get a decent mileage reading on it if I reset it and run a few miles, but once we hit the highways and actually have to GO anywhere, the mileage drops like a rock. I don't ever even push it past 72 or so, either, so it's not like I'm running it hard.

Any ideas? Going to try to get it into the dealer to run a diagnostics on it for the awful mileage this week, so hopefully that will shed some light on it. I'm just about ready to trade the frustrating thing in for an ecoboosted van, though, as at least those have a decent amount of torque to get up the hills.

 

[nc rick]

Here in western North Carolina, our van averages around 15-15.5 taking it fairly easy, empty in combined driving on local roads. The computer thinks we do better by about 1mpg.

With your tires, you are traveling more miles that your odometer tells you, no?

Otoh, on the highway we see 17 with out too much problem. Wind and hills determine 16-18 in general. Try to stay around 70. Sometimes 80 but takes an economic hit there.

 

[rob99rt]

The 13.7-14.5 mpg average is after I add 4℅ to the trip meter, fwiw. I am just very disappointed in the mileage I'm getting with it. We traded an 04 sprinter in on this van and our mileage took a huge hit from 22.0 whether it was loaded, unloaded, city, highway, etc... Seemed like no matter what we did it averaged right at 22 with the sprinter.

 

[alarmist]

My experience is much the same. Went from an 04 sprinter getting 22 to a 3.5 transit with 3.73 gears getting 13 to 14. I could get 16-18 if I wanted to drive like a nun though, so I don't blame the van. I can also get 12 if I really put my foot in it.

 

[Andre Jones]

Is this with heavy usage of the A/C? My mileage seems to take a huge nose dive with the A/c running. I've been getting 17.31mpg w/ 70% rural town roads (a total of about 3 traffic lights) and 30% highway no higher than 77. Idling with the a/c is like the black death almost one week of that took us down to the 13s.

The mileage also nose dives so far in my experience with driving much faster than 77.

Drove up to the white mountains yesterday and back, on the dash I was able to maintain 19.5mpg while hustling it, no a/c, w/ 7 of us on-board (4 kids). All speeds in this situation are lower than 60 mph and I tend to keep the corner speed fairly high and roll into the throttle real easy.

 

[rob99rt]

Is this with heavy usage of the A/C? My mileage seems to take a huge nose dive with the A/c running. I've been getting 17.31mpg w/ 70% rural town roads (a total of about 3 traffic lights) and 30% highway no higher than 77. Idling with the a/c is like the black death almost one week of that took us down to the 13s.

The mileage also nose dives so far in my experience with driving much faster than 77.

Drove up to the white mountains yesterday and back, on the dash I was able to maintain 19.5mpg while hustling it, no a/c, w/ 7 of us on-board (4 kids). All speeds in this situation are lower than 60 mph and I tend to keep the corner speed fairly high and roll into the throttle real easy.

Regarding the AC, yes. It's hot and humid here, so we have the AC going from the time we start the van until we shut it down. I've been asking my wife to keep it at 68 on the speedometer (71 mph actual via GPS), and she's done that. I do think the hills around here seem to clobber it when running around with the cruise control on, too. It'll slow down 4-5 mph and then downshift all the way to fourth after a very short time in fifth. You can practically watch the fuel gauge go down at that point.

If I drive without the cruise on and don't care so much about losing 5 mph on a hill, I'll just let it go down to only fifth and after cresting the hill pick up the lost speed again. That seems to help out a few tenths or so from what I've seen, but it makes for a busier driving experience.

 

[danketchpel]

I find running the A/C hard hurts mpg by about 1-1.5 mpg or so on my 3.2L diesel with 3.73 gears.

I might wonder if the taller tires might be hurting mpg on your van if you're running a lot of hills? I've driven in WV some and understand there's not a lot of flat driving out there. If the 3.7 engine is running below it's torque peak and having to shift down quite frequently it might drop mpg that much.

In comparison to your friend's van it seems like the one factor that stands out as different between them.

It would be interesting if you could swap rear tires with him. It's sort of a pain but might explain quite a bit.

 

[rob99rt]

I find running the A/C hard hurts mpg by about 1-1.5 mpg or so on my 3.2L diesel with 3.73 gears.

I might wonder if the taller tires might be hurting mpg on your van if you're running a lot of hills? I've driven in WV some and understand there's not a lot of flat driving out there. If the 3.7 engine is running below it's torque peak and having to shift down quite frequently it might drop mpg that much.

In comparison to your friend's van it seems like the one factor that stands out as different between them.

It would be interesting if you could swap rear tires with him. It's sort of a pain but might explain quite a bit.

I thought maybe it was the tires, but in reality it's only about 85 rpm at 70 mph, I think. It wouldn't seem that the torque curve would be much different than a few ft-lbs at 2000 vs 2080 rpm.... Not sure, though.

 

[Andre Jones]

I thought maybe it was the tires, but in reality it's only about 85 rpm at 70 mph, I think. It wouldn't seem that the torque curve would be much different than a few ft-lbs at 2000 vs 2080 rpm.... Not sure, though.

I think your 80 rpm is close, however if the lower threshold for shifting from 6th to 5th is set to 1500rpm and you're not at that due to the taller tire this could somewhat account for this issue.

One thing that may help but obviously it would also make things 'busier,' would be utilizing manual mode (M). One strategy that I personally utilize is to speed up in the flats before the hill and then take it real easy up the hill (when possible).

I also try alternating no A/C for 10 minutes on and 5 off but obviously up here in ME things aren't as sticky.

 

[Ahoelk]

Guess Ford is nor about good mileage, my 'Eco boost' 3.5 with 3.31 rear end gets 12 MPG. Not a bad van otherwise but going to the gas station a lot...

 

[unclebob]

The 3.7 engine seems adequate for city driving or light flat highway.

The 3.5 Ecoboost is more versatile. It can give you lots of power or good economy.

The trick to getting good mileage with it is being light on the throttle. It's so smooth that you may not realize how much you're into the turbos.

It's a VERY addictive engine. ??

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[brownbear]

I do think the hills around here seem to clobber it when running around with the cruise control on, too. It'll slow down 4-5 mph and then downshift all the way to fourth after a very short time in fifth. You can practically watch the fuel gauge go down at that point.

The biggest difference between the two engines is described with your quote above. That is the 3.7.

The 3.5 will not downshift and will hold the speed it's set at. I've only seen my 3.5 downshift towing my trailer loaded with 3-4K lbs in the trailer.

As for fuel economy, when the ecoboost is boosting I don't think it's efficient. I'm 17 mpg light highway. But loaded it's 13 or so. City is 15.

But I like the fact it doesn't have to downshift. Which while people think the turbo's are added complexity, the transmission on a 3.7 van is going to fail a lot sooner than a 3.5 trans that stays in lock up most of the time.

 

[rob99rt]

The biggest difference between the two engines is described with your quote above. That is the 3.7.

The 3.5 will not downshift and will hold the speed it's set at. I've only seen my 3.5 downshift towing my trailer loaded with 3-4K lbs in the trailer.

As for fuel economy, when the ecoboost is boosting I don't think it's efficient. I'm 17 mpg light highway. But loaded it's 13 or so. City is 15.

But I like the fact it doesn't have to downshift. Which while people think the turbo's are added complexity, the transmission on a 3.7 van is going to fail a lot sooner than a 3.5 trans that stays in lock up most of the time.

Right.. that extra 130+ ft-lbs of torque at 2000-ish rpms helps tremendously on the hills. The shifting up and down all the time with the 3.7 can't be good for it. On the other hand, I have wonder how much heat the 3.5's transmissions are generating running in 6th gear up and down the hills.

 

[alarmist]

Guess Ford is nor about good mileage, my 'Eco boost' 3.5 with 3.31 rear end gets 12 MPG. Not a bad van otherwise but going to the gas station a lot...

A bigger tank would have been nice.

 

[rob99rt]

I think your 80 rpm is close, however if the lower threshold for shifting from 6th to 5th is set to 1500rpm and you're not at that due to the taller tire this could somewhat account for this issue.

One thing that may help but obviously it would also make things 'busier,' would be utilizing manual mode (M). One strategy that I personally utilize is to speed up in the flats before the hill and then take it real easy up the hill (when possible).

I also try alternating no A/C for 10 minutes on and 5 off but obviously up here in ME things aren't as sticky.

Did a little test on the way to the dealer this morning and when I left the house the mileage was sitting at 14.3 mpg. By the time I got to the dealer (26 miles, with about 17 miles of that being hilly freeway, no cruise, and "attacking" the hills like somebody mentioned in another post), the mileage was up to 16.3. It might have had 50-60 miles on it to get to the 14.3 average, but the fact that it went up 2 mpg in only 26 miles of driving without the AC on is quite telling as to how much the AC kills the mileage on the van, especially with the 3.7 anyway. Ambient temps were in the low 70's, also.

Just figuring up the average MPG for that 26 miles using a weighted average equation, I'm calculating 20.53 mpg if I use a base number of 55 miles for the distance that gave me 14.3 mpg.

 

[Derrick]

We have a 2015 transit with the diesel, 148 inch wheelbase, mid roof, I believe 3.31 gears. In the course of our business, we probably have 1000 to 1500 pounds of equipment in the back of it at all times. It is definitely not driven with a light foot. There is a fair amount of freeway driving, but also a lot of stop and go, even some extended idling. And as far as mileage average goes, it is generally in the 21mpg range. I don't think I've ever seen the average get below 20. And, if conditions are right and you're just on a 2 Lane Highway going 55 or 60, you could see 25 to 28 miles per gallon. We will be purchasing another van soon, and there is no way I'm going gas after seeing what you guys are averaging.


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[Derrick]

Also, we do occasionally use this van to pull our 22 foot PowerQuest boat. If it is a freeway trip going 74 mph or so, the mileage will be in the 14 Mpg range. I don't know the exact weight of the boat and trailer combined, but I would imagine it would be close to 5000 pounds full of fuel with the tandem axle trailer


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[rob99rt]

Derrick,

That's the main thing that's given me quite a bit of heartburn after purchasing this van a few months ago... We went from 22 mpg in a Sprinter to ~14. A 36% decrease in fuel economy is crazy.

 

[nc rick]

I'm adding this from the road. Van loaded with two motorcycles and camping / riding gear / extra battery/ arb fridge etc. Knoxville,tn to Crown Point Indiana cruise set to 72 - 73mph and just go. 18.6 computer milage - 17.56 calculated. Ac on full tilt. We are still on the second tank, nearing Wausau, WI and computer is telling us 17.9-18 with intermittent head wind during the trip, blowing hard here now running a little faste today too. This is somewhat better than we get in the mountain driving conditions but I feel is typical.

Our friends Sprinter is also a 22 mpg thing. I can buy one **** of a lot of gas for what I saved vs diesel though... We sold a f350 power stroke to get this van and I like filling anywhere I want. I also anticipate lower maintainence costs.

You may well have an issue with the milage you are getting.

Hope this information is relevant and helpful.

 

[Andre Jones]

What tire pressures are you running? I'd also check the air filter and make sure it's not moist. I don't remember whose post it was but I recall an MPG drop with a soggy filter.

It seems to me you may have several small things contributing. I love the usage of "attacking" those hills, lol.

Yeah this AC seems like it has to work pretty hard. I've heard of a dropoff in mileage due to AC but it's kinda ridiculous. Probably due to a lack of insulation?