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Old 04-19-2020, 10:50 PM   #8 (permalink)
Aero Wannabe
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Join Date: Dec 2007
Location: NW Colo
Posts: 686

TDi - '04 VW Golf
90 day: 47.98 mpg (US)
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Unhappy Test Data Day One

Kudos to anyone who decides to do A-B-A testing. To do it right takes time and ideal test conditions to get good results. This testing was done over 2 days. I chose a long straight road with very little traffic and open fields on both sides. The runs were almost 2 miles in each direction at about 62 mph or 100 kph. Day one the temperature was 44 degrees with a 7 mph wind from the west. The road goes east west. I averaged the east and west runs together. I used cruise control and left the car running while I added or removed wheel covers and used the same start and stop points for all runs. I used the ScanGuage set to current MPG and reset it at the start point with the car up to speed and cruise resumed.

My A runs were with factory steel rims and the factory wheel covers with worn snow tires. The B runs were the same wheel and tire combination but with the wheel covers off.

A1 east/west average mpg- 54.7
B1 east/west average mpg- 57.85 (this was just the black steel rims)
B2 east/west average mpg- 53.6
A2 east/west average mpg- 55.85

I averaged all the A runs and all the B runs and got 55 mpg and a few decimal points for both. There seemed to be more variation with changing wind perhaps, than the variation of wheel covers on or off.
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.

Last edited by COcyclist; 04-09-2021 at 09:11 AM..
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