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New! Improved! MPG thread

18K views 61 replies 36 participants last post by  RnR 
#1 ·
I was planning to go through the existing MPG thread and tabulate all the numbers I could pull out of it, but I find there are too many unknown variables. Some posts have just mpg numbers, some have wheelbase, some have high or low roof, some have model. Some say all highway, some say all around town, others don’t say which or how much of either. Some mention heavy loads, some don’t. Some mention weather or locale; others don’t. Put it all together and I realized it wouldn’t tell me much even if I tried to sift. So, I’m hoping I can persuade folks to post to a new MPG thread, giving more info so that I can then tabulate and keep running averages going for various different configurations and uses. To that end I have come up with a list of variables to account for. I’d like first to see if anyone else has ideas on factors affecting MPG that I have not thought of. Once we have a list then I can come up with a format for the info that would be easy to fill out so we get usable data.
My list:
Wheelbase
High or low top for the 136’s
1500/2500/3500
Diesel or gas
Roof rack or not
Boats on roof or not
Rooftop solar or not
Loaded, empty, or in between
In town on on highway
Towing & what sort of trailer
Climate/locale/season
Camper or work van
Roof vent or not
Jackrabbit or turtle:)
Tires
Modifications to suspension
Age/mileage of van
Equipment on underbelly (tanks, etc.)


Anyone else think of anything else?
 
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#2 ·
Great thread ! I think you covered every variable . Could add " Sweet Spot" MPH vs MPG . Our little Transit Connects really drink the gas over 75 MPH , the 4 banger has to work to push that box thru the air , not so bad at 65 thou .
Charles Lindbergh calculated if they slowed down the P-38s they could increase range by a 1/3 or so .
 
#3 ·
Winds (headwind or not)
Elevation change (downhill, uphill or flat)

I like the idea of the details to get a better handle on this but that is a lot of information to ask for. Maybe some kind of checkbox form would help?

I like hearing what others think of the sweet spot. I find 60 MPH is a great place for MPG on my gas 159 high top. 21 to 24 MPG [emoji4]

Sent from my SM-N950U using Tapatalk
 
#25 ·
Your info is spot on with what i have found. I have a 2016 159" HR gasser and if its fairly level i get about 22-23mpg at 60-63 MPH if you go t0 70 it drops to 16-18. best i can do in the mountains of PA and WV is 18.5 mpg highway at 60-63 MPH and my 22-23 mpg was loaded to 7900lbs
 
#4 ·
This one is hard to get a handle on, but can have a small effect on mileage due to varying energy content: Grade of gas and enthanol content.

E10 is most common, but there are regional and seasonal variations. This might be splitting hairs, as the effect is supposed to be at most about 4-5%.

Others thoughts are: tire pressure, grades or terrain, cruise control use and any ‘coasting’ strategies.
 
#8 ·
I think the average speed for the tank tells the truth regarding city/highway. I know mine is 29-31 mph every tank. I also run the AC all the time. Gas 136" High 1500 with 1000-1200 lbs tools/parts at all times and just 2400 miles. Right at 17 hand calculated. Nothing on the roof and I am a turbit. More turtle than rabbit from stops.
 
#17 ·
I think the average speed for the tank tells the truth regarding city/highway.
I agree that Average Speed is a significant factor. It is also an easy and objective number to record. I think the big challenge in comparing mpg is getting everyone to report information in the same way.

If you want people to participate in a more scientific survey, it will need to be fairly simple and straightforward. If people can record info about their vans once, then add a few numbers with each fill-up, it might work.

Also, I wish that people would always indicate if they are reporting calculated mpg, or computer-estimated mpg. We know those are rarely the same. Perhaps it would help to use abbreviations, such as "calc" and "comp" after the reported mileage(?).
 
#9 ·
Definitely some good additions. Now I need to come up with a way to set this up - maybe a form - so that it will be easy enough for folks to put the info in. I think I'm going to have to edit it down somewhat on the number of points. It would be great to have more data but I think if I ask for too much I will end up getting less rather than more.
 
#10 ·
What most affects my in-town mileage here in Austin is not so much the hills as you go up those and go down them but it's the sitting in traffic and at red lights. Some are towns and some are busy cities. Might specify in-town or in busy conjested city.
 
#14 · (Edited)
You need to automate something like this from my diesel. No matter what magic pencil you use everybody's mpg will be different if you look on fuelly.com no magic pencils there, their all different from what people report on this fourm.
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#19 ·
After mounting my solar cells on the roof I found I lost an average of 1 mpg hiway. Driving to Fl. last year on I 95 we'd get 21-22 mpg if I slowed down to 65 mph. Get it to 70 or above and it drops to 19. Came home from Asheboro NC last weekend loaded with camping gear. Took mostly back roads to get home. 45 to 55 mph speed limits. Got 23.5 average for the trip home! Only got 19.5 mpg on the way there as using I 95 at 70 mph and then a huge traffic back up for half an hour, really killed the fuel economy.

All in all, I'm pleased with it! You can drive all day on a tank of gas!
 
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#21 ·
Might seem like a lot of work, but interesting to me. I'm not in a hurry, and gathering a lot of data is my way of doing it when it come to vehicle decisions. And sure I can guess at all the factors, but that is still guessing. And average does not mean much in this case since there are so many variations over such a large range. Average of all promasters does not mean much compared to average of all the 118 low roof lightly loaded no roof rack versions driven by folks not in a hurry who drive mostly on the highway, or all the 159 high roof extendeds with solar and kayaks on the roof driven by leadfoots on dirt roads most of the time. One would expect a substantial difference between those two averages, and I'd sure like to see what it is, and I haven't seen anything like that anywhere yet.
 
#22 ·
3500, 3.6 engine. It is a Dynamax Rev weighing about 11,000 loaded. Just got back from Fl Keys, about 4000 miles round trip. I got between 15 and 16 mpg. I never drive it over 65. It only has single wheels on the back. Also had it all over Colorado and Utah. I am in Illinois. Still 15 to 16 mpg. Im very happy with that.
Ron
 
#26 · (Edited)
Working on format. But I realized I am not sure about how many different diesel versions have been offered at one time or another. So here is what I am guessing to start with: please let me know if I am missing any or if I have made up any that never existed.


1 118 wheelbase 1500 gas
2 136 wheelbase 1500 low roof gas

3 136 wheelbase 1500 low roof Diesel

4 136 wheelbase 1500 high roof gas

5 136 wheelbase 1500 high roof diesel

6 136 wheelbase 2500 high roof gas

7 136 wheelbase 2500 high roof diesel

8 159 wheelbase 2500 high roof gas

9 159 wheelbase 2500 high roof diesel

10 159 wheelbase 3500 high roof gas

11 159 wheelbase 3500 high roof diesel

12 159 wheelbase EXT 3500 high roof gas

13 159 wheelbase EXT 3500 high roof diesel
 
#28 ·
159 ext. gasser. Travato. Averaging 14.5 in first month of ownership. I tow an open trailer with 2 motos and have a load of gear, so pretty heavy most of the time. I drive it only fast enough to keep up with traffic (barely). I was hoping for a bit better. My 118 sprinter with the same load got 20. Apples and oranges of course.
 
#30 · (Edited)
Mileage 2798 from recent trip from Mpls, Mn to Escalante, Utah and back traveling thru Ia, Ne, Co via mostly interstate highest elevation attained appx 11,000' Eisenhower tunnel Loveland pass Co, Van started trip with 8000 miles on the odometer and using conventional oil and will be switching to synthetic after next pending oil change. I drove the same route coming and going so what I went uphill going I came downhill coming back and visa versa variable would have been wind.

136WB LR stock configuration with 800lb load.

Worst 18.4mpg hand computed into 25-30 gusting to 40mph quartering headwind at 60mph, Gusts where bad enough making it difficult to maintain lane position so I lowered my mph.

Best 21.1 mpg hand computed, 67mph average no idea on wind conditions.

I am closer to being a turabbit no rush going for mpg rather than how fast I can get there compromise, Out of curiosity on one stretch in Utah I ran it up to 75mph with a 20-25mph tailwind and had a computer estimated 21.5mpg for appx 30miles I then dropped back to my 67-68mph average.


My perspective 55-60mph gives better mileage but to slow, No appreciable mpg difference between 65-68mph and mileage starts going downhill noticeably around 70mph so my personal compromise is 67-68mph.

Miles driven 2798 fuel used 137.5 gallons, Trip average 20.34mpg average speed 67-68mph
 
#39 ·
1500 RPM calculates to only 50~51 MPH in top gear, so 16 MPG seems disappointing for a Travato based on other reports I’ve read. Any chance your motorcycle trailer is dragging due to brakes, or misaligned wheels? Do you have similar MPG data without the trailer?
 
#33 ·
3500 built out diesel through the mountains of Colorado. Usually full of water/etc

I drive around the speed limit, depending on how many road beers we've had :) so 65 in the mountains and 80 in the plains. Average out to about 22 mpg in the diesel. 21.9 mpg on the last tank. If I drive on the back roads where it's 55, and I actually do drive 55, I can get a bit higher, but meh, I'd rather pay a few more bucks and get there faster.

That is calculating the "actual" based on miles and the amount of fuel I put in. The onboard computer says 21.0
 
#34 ·
I don't know why, and it seems counter-intuitive, but my usual out and back mileage for a local camping trip into the mountains has improved from 16.9 to 17.4 since I started using the tow/haul mode. It's a mix of freeway, country roads and unpaved washboard.

These numbers are from the onboard computer.
 
#35 ·
OK , My loose numbers :
118" lightly loaded , no external "drag" items .
70 mph speed warning on dash , Tow/haul in twistys/mountains , "vacation" mode driving style .
About 340 mile loop .
19 mpg .
I am ecstatic about that .
Still don't know about a sweet spot .
 
#36 ·
I’ve been doing a 320 mile out and back round trip to help a friend renovate a house he bought to resell. There were lots of pavers and wall landscape blocks to remove so I have been pulling my 5X8 landscape trailer to retrieve them. 25.6 going empty and 24.2 returning with 1800lb in the trailer. I live at a lower elevation so there is some coasting in 6th coming home. This week I go w/o the trailer and hope to get my “normal” 26+ These are calculated as the readout shows about 1mpg less. Diesel of course.
 
#42 · (Edited)
I just got back and did 26.4 mpg w/o the trailer. I am super impressed how little the trailer changed my mileage. 2/3 interstate 65+- and 1/3 two lane 50+-
 
#38 ·
2017, 2500, High-top, 159 WB, Gasser, Sunlight V-1 class B, A/C on top and awning sticking up also. Took off from Surprise AZ to Stephenville TX and return probably weighted in around 10K, not towing. Drove between 70 and 75 MPH (got to get thru that boring west Texas drive) on I-10 and I-20, pretty strong side winds on I-20 both ways. Started out with about 500 miles on the clock, trip total was 2218.2 miles, used 140.3 gallons of gas at a cost of $410.16 and averaged 15.8 MPG hand calculated. I'm a happy camper so far.


Bill
 
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