[mattW]

This section aims to present practical methods for measuring data relating to the aerodynamics of electric vehicles. This data may aid in flow visualisation, design of aerodynamic modifications, testing the effectiveness of modifications, determining power requirements, vehicle efficiencies and more. These testing methods should be relevant and accessibly to the average EV hobbyist (so wind-tunnel testing and expensive computer simulations are outside the scope of this wiki).

Wool Tuft Testing
The following links describe a simple DIY test to aid in determining the flow characteristics of your vehicle in order to determine where positive improvements can be made. It is a five part series, but the main ideas are covered in the first link.
http://www.autospeed.com/cms/A_108656/article.html
http://www.autospeed.com/cms/A_108674/article.html
http://www.autospeed.com/cms/A_108675/article.html
http://www.autospeed.com/cms/A_108676/article.html
http://www.autospeed.com/cms/A_108677/article.html

Measuring the Coefficient of Drag (Roll Down Testing)
This link describes in some detail how to accurately measure the coefficient of drag and rolling resistance of your vehicle using a simple roll down test from 70mph (120km/h):
http://www.instructables.com/id/S41H3Y4F5Y3TMFX/