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Discussion Starter #1
I know there's been comments in the "Diesel!" thread about mileage, especially reports from the road by Adrian. There's also diesel entries in the "Any real mpg #s yet?" thread, but they're rather hidden in there, and not always clear.


So... thought we'd get our own diesel mileage thread going. Be able to 'show off' our results here. Have a single place where folks curious about the performance of the diesel can see real-world results.



Starting off:


I just made the first fill-up in my diesel PM.

I couldn't bring myself to wait for an empty tank, filled up just below half tank at ~330 miles. Was quite a bit of easy around town driving, with some short 55mph freeway commuting time, and a few moderate throttle pulls up some longer hills.

Dash computer had the mileage at 24.6, calculated mileage was 24.1.


 

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I have 5000 miles on my 136" high roof with no problems and, most importantly, no CELs. I typically drive about 40% in town and 60% 4-lane/ interstate. I am usually unloaded but some times have a load of two motorcycles (about 900 lbs.) I average 24.5-26.5mpg depending on load, speed, wind and terrain. I usually don't drive faster than 67 mph and almost always manually shift the tranny.
 

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118 diesel loaded heavy with tools, heavy traffic 25%, highway 50%, running around town late, up and down hills 25%. Averaging around 23, best on vacation was 26 lightly loaded from Medford to crater lake and back. Loaded and a 10' utility trailer around 20. All hand calc. Love it. Only problem was a new starter around 2000 and a CEL around the same time. Total of 7000 now with no problems.
 

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I have around 19,000 miles on my Hightop Ext Diesel ....I drive 80% freeway and Average around 23 mpgs . Not much of a load in the Van....maybe 1,000 lbs. I absolutely love this Van....and more importantly, my wife likes it just as much!
 

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nielswheels,
Calculated or computer and how do they compare? Some folks find the computer close but many have reported the computer is as much as 3mpg low.
 

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Did some right-lane below speed limit cruising yesterday - so miles 1200-1600 on 4-week old 159" window van were from Joplin, MO to Des Moines, IA...

84-95ºF, clear, no wind, Sinclair #2 diesel w/ bug massacre velvet paint & glass... maybe 750 pounds over delivered dry weight... 26.6mpg calculated, fuel was $2.55 credit price.

I'm very much in 'like' with this van.
 

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Remember what the trip computer is doing. I takes a reading of the instant mileage at regular intervals, then justmakes an average.

So if i drive up and down Pikes Peak, it will show 8mpg on the way up, then on the way down it will show 99mpg, and the whole trip will calculate to 50mpg, which you know isnt accurate.
 

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Remember what the trip computer is doing. I takes a reading of the instant mileage at regular intervals, then justmakes an average.

So if i drive up and down Pikes Peak, it will show 8mpg on the way up, then on the way down it will show 99mpg, and the whole trip will calculate to 50mpg, which you know isnt accurate.
Why do you think they do it that way? It would be just as easy, or easier computationally to keep a sum of the fuel used and the miles and figure it from that, which would correct.
 

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Computer was always 1 mpg less than what we would figure adding the miles and gallons...very happy with 23 mpg....my 40ft RV only gets 7 mpg ! We are saving so much by taking to van....and there is a bonus....we can Flat Tow the Promaster behind our RV if we wish. ! It's in the manual.
 

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As i understand it, a manometer - a device that measures fluid flow - is a fairly expensive proposition. So they use the injector pulse with (how long the injector is open and at what pressure) to derive how much fuel has been used.

The only other sensor would be the fuel level in the tank, but thats a pretty coarse input to try to calculate mileage from.
 

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Computer was always 1 mpg less than what we would figure adding the miles and gallons...very happy with 23 mpg....my 40ft RV only gets 7 mpg ! We are saving so much by taking to van....and there is a bonus....we can Flat Tow the Promaster behind our RV if we wish. ! It's in the manual.
That's pretty sweet. A great vehicle to drive once the RV's parked and tons of extra storage!
 

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The other day I was behind another promaster on a1a (flat 55 mph) insta was reading 32-33. I was rather surprised so I turned on cruise and my average was above 30 for the rest of the 20 mile trip. Drafting sure does help. My overall average of mostly city driving is 21/22, but I'm idling an hour + a day.
 

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For that last run I posted on I'd sure found a problem with driving mildly - no one to draft, at least here in the Midwest. Back East (I-95, I-81, Beltways, etc.) many semi's have speed limiters and the drivers seem resigned to having little fish swimming in their wakes.

The 26.1/26.6mpg I posted above - 1/2 mpg under-estimate for each of four tanks so far; no full throttle runs and no playing to goose shift points; keeping a rolling 15-second look ahead, the distance you will travel in 15 seconds... mellow driving. The 9.5¢ per mile fuel cost isn't the only payback - sitting down with the Insurance people they said I've been with them for 33 years with zero claims and I selfishly want to keep it that way.
 

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Diesel PM, 2015, 2500 hi-top
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Over 7K miles on diesel average is 28 mpg

When I first got my diesel high-top last January, there were several CELs but no driving/motor issues, dealer installed a new EGR unit. Since then, no CELs, no issues, all is fine, love driving it, love traveling in it, love shifting the manual gears, love parking it, love it love it love it!!
Trip A has never been reset, over 7K miles so far, average is 27.8 mpg which is a mixture of everything from Texas to Washington DC to Montreal to the Midwest. Trip B was done recently on a boring flat road with no wind and no traffic (just rural midwestern crop fields for about four hours of driving). I kept the speed between 45 and 48 mph in sixth gear, engine didn't lug, engine was purring happily, and my highest average during those four hours was 31.3 which amazed me. Staying under 50 mph isn't always a good idea on major busy highways, so I'm not recommending driving under 50 mph to save fuel. Just wanted to see for myself . . . .
 

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Discussion Starter #17
Second fillup tonight. Still had some fuel left, but its heading out on a road trip this weekend, like to start off full.

Mostly around town driving with some freeway blips and a bit heavier on the throttle to work on the engine break-in. (I'm at 750 miles, I guess its good enough for some long freeway cruising)

Came out at 22.7mpg calculated, over 364 miles. Computer had it at 22.6mpg.

Filling up so far with Chevron diesel. I think its labelled as the usual 'up to 5%' bio.

Currently at 23.4 overall. Will be interesting to see how it does on the road trip this weekend. My girl will probably be driving it ~70mph (speed limit), and up and over Snoqualmie pass. Still, expecting something in the mid-20s.


 

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Discussion Starter #19
Haven't filled up yet, but the girl took the van over the Snoqualmie to Seattle last weekend. I looked at the Trip A when she got back. ~420 miles, 61mph avg speed, and 22.3mpg. :( Was hoping for a bit higher than that on the road, but it was probably 70mph on cruise up the hills. I'm taking it to Portland in a few weeks, see how it fares on the relative flats of the Columbia River Gorge (that is, if there's no wind).
 

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Diesel PM, 2015, 2500 hi-top
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Speed kills good mileage, and bio-diesel - where is it?

I don't buy "brand name" diesel (Chevron, Shell, etc.) I just stop at the cheapest place. I also check the pump to see if it's blended with bio, and since purchase in January, with travels in all states from TX to NC to NY to Canada to Montana, I have NEVER seen a diesel fuel pump station with an explanation of the bio content if any. Once I asked the clerk in the convenience store if there was any bio-diesel content and he looked at me like "huh??" If there is any bio-diesel, does the pump tell me exactly what the ratio is? And if there's no ratio report, does that mean it's five percent or less?
On the great mileage I'm getting, I drive very slow on seldom-used rural roads most of the time, average speed is 42 mph. When I'm on the major roads, I'm at 65 mph however. Mostly, I'm a sight-seer, but if someone's behind me, I pull over at the first opportunity.

My build-out blog is here, if anyone's interested:
http://lalaironwheels.blogspot.com/
 
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