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Old 12-31-2009, 02:58 PM   #15 (permalink)
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Originally Posted by Fubeca View Post
Well - it was a terrible day to do any real testing but it was the only time I'll have for a while.

I warmed the truck up and drove back and forth on a 1.5 mile stretch of straight rural highway.

I ended up doing a B-A-B-A test. Each leg was 4 sets of out and back.

B: avg mpg 19.6
A: avg mpg 18.8
B: avg mpg 19.4
A: avg mpg 18.8

So it looks like a lackluster improvement of ~.7 mpg or ~4%

The ambient temp was 10* and there was a NW wind at 10-15 mph. The road was East to West.

So I don't think the test is really all that valuable. I'll be interested to see how my mileage looks over time.

I'll take some more pics and maybe you all can let me know if you see any areas that may need improvement. I was really hoping to get 10 - 20% improvement.
I suspect that if you had immediately yanked the cover and did the same runs "naked",that you would not have seen your 17.58mpg baseline.
I've been looking back over the logbook on my truck and it will lose almost 9 % mpg between winter and summer.
I really think that 10-degree temp is slamming your numbers,that's why I posted the general temp/mpg chart.Your 19.6 might become a 21.364 mpg in August.
It takes 22-miles of continuous driving at 50-mph just to bring a vehicle up to it's equilibrium temperature for any given ambient condition.Any parking time between runs,even a stoplight can cost you in heat transfer.
I like your cap a lot.Please spend some time with it and see that,when things warm up again,she doesn't go even further between gas pumps.
I tore my hair out the winter of '05/06 hoping to see my bellypan show up on the radar.It wasn't until spring that the numbers emerged.
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