I went through the coastdown data and got some numbers. Since it turned out that the test track is sloped, I decided to process the 'E' and 'W' runs independently. I used the spreadsheet you can get from
IWillTry.org to find the Cd and Crr coefficients. I modified the spreadsheet for 5 second intervals instead of 10sec.
No mods:
| . | W | E | Both |
| Cd | 0.333 | 0.335 | 0.334 |
| Crr | 0.0110 | 0.0180 | 0.0144 |
With mods:
| . | W | E | Both |
| Cd | 0.334 | 0.325 | 0.324 |
| Crr | 0.0100 | 0.0155 | 0.0130 |
In the 'W' runs it appears that Cd
increased, but when including all runs it dropped from 0.334 to 0.324. That's not much
The roof rails and mirror did change frontal area, though. I guess you can't really change much in a 1.5 ton cow with the FA of a barn. Maybe I'll find a better, flatter road with less traffic somewhere around here and repeat the tests.
Yesterday evening the Wife was looking at used VW Lupos, the 3L versions. I looked over her shoulder and got jealous. Those things are so small, and weigh only half as much as Svietlana. Well, we both know that there's no reason to have two cars when we don't use the one we have too often.