2017 170 EXT 3500 Fuel Economy Concern

vanscum

New member
A couple months ago I bought a 2017 cargo 170 ext 3500 4x4 off the lot in Canada. I'm in the process of converting it into an RV but while It's been empty I've made a few long highway trips and I am starting to be concerned with the fuel economy. On average, It stays between 14 and 15 l/100km (16.8 - 15.6 mpg) on the highway. This is on a combination of flat, rolling, and mountain pass terrain and doing 90 - 110 km/h (55 - 70 mph). It'll climb towards 16 if I am only driving up a mountain, but usually things will even out and come down to just under 15. The fuel light will come on consistently around 450km (280 mi), and I can push it to about 580 before I need to stop.

I am concerned for a couple reasons:

1. The Mercedes sprinter sales folks have consistently seen 11 l/100km (21.3 mpg) in the same van as mine, fully loaded on the highway, and around 12-13 in the city.

2. I'm seeing older sprinters get better mileage. A specific example is a 2014 170 ext airstream interstate, fully loaded, getting 13 l/100km over mountain passes. This example is from today. After 440km, 5h 12, over 5000ft of elevation gain averaging 86km/h he ended up with 13 l/100km, a half tank remaining and estimated range remaining of 420km. This is obviously a bit slower than 100 km/h average, but I've only actually seen 13 a few times at the start of trips and it always rose pretty quick into the 14-15s from there.


I've already had it in to the dealership. They updated the CDI software, but otherwise saw no issues. Their report said they were getting 10.6l/100km on a highway test drive. I took it out right after on the highway and managed 14.1 for ~50km at 100km/h.

Does this seem worth investigating further? If so, how would I go about it considering the dealership has yet to find an issue?
 

brianszero

Active member
This has been covered before but here goes.
I have a 2016 144 4x4 and my average is consistently in the 15mpg. If I go easy on the highway I can get 17mpg and thats about 70mph max. If I am driving highway up and down mountains and going 80+ I get 14's..

Yes this is also with BFG's
 
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vanscum

New member
I've searched and read and see that others on the internet seem to get similar values, but I'm struggling to explain the concrete examples of other vans with the exact same specs getting far better mileage on a regular basis.
 

sailquik

Well-known member
OK guys,
How many of you are using a ScanGauge II or similar performance monitoring gauge package?
How many of you are aware that the 5G-Tronic/NAG-1 transmission you have is notorious for refusing
to auto downshift out of overdrive (0.83 : 1 5th gear).
Do you realize that by not manually downshifting when the % engine Load exceeds ~85% you are often using
2-4 times as much fuel lugging along @ <2500 RPM than you would if you manually downshifted the transmission
(4th gear is 1 : 1 through the transmission) to put your Sprinter in a better RPM range (2700-3300 RPM) and
into a gear that will give you better fuel mileage because the gear ratio is better and the RPMs are in the most
powerful/best fuel mileage range.
With a ScanGauge II (or similar) you can actually use the GPH to see, in real time, that your Sprinter is using
significantly less fuel, to go the same speed, at a lower % engine load/better RPM Range/more advantageous
gear ratio.
When your fuel consumption decreases from > 4 gal/hour to 2.5 gal/hour, at the same speed, in a lower/better
gear (manually downshifted) it will get your attention.
Roger
 

vanscum

New member
From what I understand it was the 4cyl w 7sp trans that got the "good" mileage

Bob
My references are same body and engine size as mine - 6cyl 5spd. I can jump in my friends 2014 Airstream right now and get 2mpg improvement over my 2017 which is completely empty inside. The van guy at the dealer is claiming he has personally delivered the same van as mine while getting 21+ mpg. Even if the last example was somehow exaggerated, the numbers on the 2014 were pulled from a trip done today, and I've taken trips in it myself and found the same results.
 

Old Crows

Calypso 2014 View Profile
Your mpg in a 4x4 compares well with our '14 View Profile 4x2 3500, V6 5 speed. Mid 15 mpg on average. (14.5 to 16.5). Much of your fuel economy depends a combination of factors. Speed, acceleration, weight, terrain, weather, traffic, idle time, type of tires, oil grade, tire pressures, etc.. They are much more of an influence than a "mechanical" issue especially since the dealer has found nothing wrong.

21 mpg in a 4x4 is a bit of a stretch I'd think.
 

Flagster

Active member
Well within range of normal...I only get excited about anything getting over 30mpg....haha Like our slug 2.5l cvt subaru...
The 4x4 3.0l sprinter I think hovers around 17.5...converted..I'm pretty happy with this as our two Land Cruisers average 11.5 between the two of them...
 

Moto Vita

Active member
A couple months ago I bought a 2017 cargo 170 ext 3500 4x4 off the lot in Canada. I'm in the process of converting it into an RV but while It's been empty I've made a few long highway trips and I am starting to be concerned with the fuel economy. On average, It stays between 14 and 15 l/100km (16.8 - 15.6 mpg) on the highway. This is on a combination of flat, rolling, and mountain pass terrain and doing 90 - 110 km/h (55 - 70 mph). It'll climb towards 16 if I am only driving up a mountain, but usually things will even out and come down to just under 15. The fuel light will come on consistently around 450km (280 mi), and I can push it to about 580 before I need to stop.

I am concerned for a couple reasons:

1. The Mercedes sprinter sales folks have consistently seen 11 l/100km (21.3 mpg) in the same van as mine, fully loaded on the highway, and around 12-13 in the city.
Funny how the folks selling them are the ones seeing the good fuel economy.
My 2016 3500 4X4 Roadtrek RV averages about 16 mpg. I drive in the land of 75 mph speed limits though.
 

vanscum

New member
I suppose the View Profile size difference compared to a '14 Airstream Interstate would explain the up to 3.5 less mpg you're getting in comparison. And considering the 4x4, I can see how the height as well as the constant extra drag that is supposedly placed on the drivetrain even when 4x4 is not engaged (which I hadn't fully considered) could cause a significant reduction in mileage. Perhaps I should find a way to test this, as I do have full access to that '14 at the moment. An OBD2 comparing load percentage on a controlled route maybe.
 

vanscum

New member
Well within range of normal...I only get excited about anything getting over 30mpg....haha Like our slug 2.5l cvt subaru...
The 4x4 3.0l sprinter I think hovers around 17.5...converted..I'm pretty happy with this as our two Land Cruisers average 11.5 between the two of them...
17.5 seems pretty acceptable for a conversion 4x4. My concern is that I'm at 16 now while empty. That last thing I want is for there to be something wonky before I load 'er up and then be stuck down at 12mpg. But it sounds like I need subtract a bit more for the 4x4 than I had originally thought - ~2 mpg maybe. And I could give an OBD tool a shot to see if my driving habits could be partly to blame.
 

zither99

Active member
FWIW
Lifetime averages for 3 vans I owned/own
my 2007 Dodge 170" non extended did about 14.5L/100km average
my 2014 4cyl 170" did 12.9L/100km average (best 9.7L/100km, empty van trip to Jasper from Edmonton and back)

my 2015 4x4 170" has 16L/100km

same usage, same cargo inside, around the city and freeway

on a 2 week trip throughout British Columbia and Montana in the summer of 2017, average was 12.5L/100km for the whole trip, doing 80mph/full blast where it was possible
 

brianszero

Active member
^^^^^ exactly.. The difference between 70 and 80full blast is huge. I just don't have enough control or patience to drive 70!! maybe someday?
 

RVCuisineScene

Active member
I picked my 4X4 3500 2017 van in Pennsylvania and drove it out to the western slope of Colorado in Jan. (2500 miles). In Feb I took the van on a trip to Sedona AZ loaded with bikes, bed and camping "stuff" (1000 miles). After factoring out the first 1000 mile break-in period I averaged 18.4 mpg on these trips, driving at the speed limit to +5 over. IMHO driving habits can be a factor, I accelerate slowly and try to drive like my brakes don't work, (in the 80's I owned a VW bug which had "temperamental" brakes).
I've started my conversion so I will see what happens as I add more weight. So far the two tubes of caulk on the trim tabs, Noico tape, Espar heater, Thinsulate insulation, Queen bed with frame and 3rd passenger chair have had no effect.
 

vanscum

New member
18.4 for a 4x4 3500 sounds good, and seems to be the average. I'm far below it, which is why I raised my concerns. When I picked mine up from the dealer, I was getting ~15, and since then has only improved to around 16 highway. I drive it pretty easy, and the best I've ever seen for a 4 hour + highway trip in Alberta was 16.8 doing the speed limit.
 

sprint2freedom

2008 NCV3 170ext
Want better mileage? Slow down. Go 55mph instead of 70.

Drag is proportional to cross sectional area, and the square of velocity.
 
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Moto Vita

Active member
18.4 for a 4x4 3500 sounds good, and seems to be the average. I'm far below it, which is why I raised my concerns. When I picked mine up from the dealer, I was getting ~15, and since then has only improved to around 16 highway. I drive it pretty easy, and the best I've ever seen for a 4 hour + highway trip in Alberta was 16.8 doing the speed limit.
How do you come up with an 18.4mpg average? Most of what's posted here is below that, where are the higher mpg reports to come up with that average?
 

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