I did today some coasting testing.
Temperature was +17 celsius so RHO~1,2176
120-80km/h north avg time 36,92s south 36,11s--> total avg 36,52s
40-20 km/h north avg time 65,18 south 75,68 --> total avg 70,43s
Frontal area is 1,8772 m2
weight 890 kg
Based on ernies formula
Cd=((M*a-crr*M*g)*2)/A*rho*V^2
What speed should I use or have I made a mistake in the formula?
Someone with computer skills should make similar exel sheet like this:
Drag Coefficient Calculation