Long_for_the_road
Chandler, AZ
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Joined: 02/15/2005
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Following data for our van (5.4L, 4 spd auto, 3.55 final drive ratio, high top, 1999 Ford E350 van, with 196,500 miles on it). We drove a local freeway loop that is slightly more than 20 miles, so 120+ miles total.
Lap.....Speed*....MPG**
1.......55........18.8
2.......75........14.8
3.......55........19.2
4.......75........14.8
5.......65........16.7
6.......65........16.8
*speed is per the speedometer, which indicates about 5 mph high at 60 mph
**MPG is per the trip mode of the ScanGauge. It seems to match our observed long term trip MPG of approximately 16 mpg (we generally drive 65-70 mph indicated)
Anyway, I was surprised how much difference it actually makes (again, assuming the scan gauge is accurate).
Using 65 mph as the "base" case, MPGs improved about 13% when we slowed down about 15% (to 55 mph), and decreased about 13% when we sped up by about 15% (to 75 mph)
Driving 55 mph is pretty tough - but I thought it would be useful to know the tradeoffs.
Shane
'99 Ford Extended van (converted)
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AsheGuy
Raleigh, North Carolina
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Joined: 11/15/2004
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Wow Shane, you have too much time on your hands and you are not even retired. 
Interesting data. I just got a ScanGauge for our LTV but I am not sure I am going to go do loops around Raleigh to duplicate your data. Our inner loop is also probably ~20 miles but I estimate it would cost me about $24.00 to perform the experiment. I would say the spread of 4 MPG between 55 and 75 MPG is close to our experience with the LTV.
David & Margaret - 2005 LTV 210B 3S
- Our Blog -
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juliev
Minnesota
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Joined: 07/29/2004
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I've noticed a significant difference too, between Chino and I driving. I tend to drive 60 - 65 MPH on the interstate, he drives 70 - 75 and is more aggressive. I just putz along and take my time. I definitely can get better mileage. On a 2 lane highway at 55 MPH I can get about 23 MPG.
Julie
_____________________________________________________________________
A good traveler has no fixed plans, and is not intent on arriving. ~ Lao Tzu
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Long_for_the_road
Chandler, AZ
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Quote:Wow Shane, you have too much time on your hands and you are not even retired.
Well... you know.... sometimes you just get tired of wondering. And some of us are just geeks - sad, but true. I felt a little guilty about burning the fuel.
Sometimes it's just fun to do the geeky, weird things that my friends don't necessarily understand - but I enjoy.
Last weekend we drove to Tucson & back (on that trip we had a purpose). We tried different speeds, and it seemed to have a larger effect than I would have guessed - but the road isn't really flat - so it was hard to say with confidence.
Maybe its useful information to the group. Maybe it's just a waste of forum real-estate.
Oh well...
Shane
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AsheGuy
Raleigh, North Carolina
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Joined: 11/15/2004
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Long_for_the_road wrote:Maybe its useful information to the group. Maybe it's just a waste of forum real-estate. I wasn't knocking you, just a little humor. 
It is useful information.
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ennajean
Wisconsin
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Joined: 05/19/2006
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Found this data very interesting....Now to get my husband to slow down and save a couple of bucks on gas.
When you see the difference in writing it sure does make a good visual impact.
Anne and Dick
DABEE a 2006 Ford Sportsmobile Penthouse top.
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Ms"B"Haven
Tennessee
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Joined: 12/09/2007
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Thanks for burning your gas to make us a little more knowledgeable about mpg. I think it is pretty accurate info. On my trip to Wyoming I did a lot of 70-75 mph and only got 19 mpg instead of my usual 21 mpg. I tried to do 55 mph on the trip, but it was just too slow and everyone was passing me.
2003 Forest River M-B Cruiser 22'
www.rv-adventure.blogspot.com
Annie B, Buddy & Penny (Chihuahua) & Holly (Maltese)
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CSG
ID
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Joined: 03/02/2001
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I find driving 55-60 rather leisurely and, being a cheapskate, like getting better MPG. When we drive my wife's Camry Hybrid though we always go the speed limit (usually 75 MPH here in the rural west).
BTW, I seem to get 16-19 MPG in the Traverse. It's got the 5.4 V8 but a 3:73 rear axle IIRC. The 2002's were built on a light E250 (7200 GVWR vs. 8600).
2001 GMC EC 2500HD, 4x4, 6.0 V8
2007 Nash 27-5B
2002 Pleasure-Way Traverse
1990 Lance Squire 4000
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REK1
San Jose
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Joined: 09/21/2006
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Ms"B"Haven wrote:Thanks for burning your gas to make us a little more knowledgeable about mpg. I think it is pretty accurate info. On my trip to Wyoming I did a lot of 70-75 mph and only got 19 mpg instead of my usual 21 mpg. I tried to do 55 mph on the trip, but it was just too slow and everyone was passing me.
This is similar to our experience. We have had a high of 26.25 mpg going a flat and steady 55 mph and a low of 18.75 mpg at 75 mph. As much as I try to enjoy the increase in fuel savings by going slower on a long trips, it is very hard to do on a trip of 500 miles as it would take us almost 2-1/2 hours longer. Ron
Ron - Roadtrek RS Adventurous
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CSG
ID
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Joined: 03/02/2001
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Ron, is it about the journey or the destination? I sort of prefer the journey myself and am in no rush.
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