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Old 02-21-2012, 06:27 PM   #25 (permalink)
Aero Wannabe
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Join Date: Dec 2007
Location: NW Colo
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TDi - '04 VW Golf
90 day: 47.98 mpg (US)
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Originally Posted by jamesshaw89 View Post
I took the front air damn off after driving to Cincinnati and back and not seeing much of an improvement followed by a coast down test on a local hill I went from 40-56 on Friday without the damn, skirt or wheel covers! but today I went 40-53 with the dam/skirt/wheel covers and 40-52 without the dam but with the skirt/wheel covers. I was getting pretty annoyed after not going faster but maybe today I had a head wind and Friday I had a tail wind? I had driven the car for 20 minutes to make sure everything was warmed up...
Coast down tests are very difficult to do accurately. Done on different days they are almost worthless. Wind speed, direction, temperature, atmospheric pressure, temperature and humidity can all effect your results. Keep trying, eventually you will see what works.
60 mpg hwy highest, 50+mpg lifetime
TDi=fast frugal fun

Originally Posted by freebeard View Post
The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.
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