Parameters

v= 50 km/h = 14 m/s

A= 0.8 m2

d = 500 m

efficiency = η= 85%

mc = 900 kg incl. 100 kg battery

ρ = 1.3 kg/m3

First I have calculated the power of the EV with a speed of 50 km/h and 100 kg battery.

Power car= 1/2η [m v^3/d+ρAv^3 ]=1/(2×0.85) [1000×〖14〗^3/500+ 1.3 ×0.8×〖14〗^3 ]

Power car = 4.91 kW

Energy density battery = 200 Wh/kg. With a 100 kg = 20 kWh

Driving time on a full charge (hours)=(power of battery (kWh))/(power of car (kW))=20/4.91= 4.07 hours

Range (km)=Speed (km⁄h)×time (h)= 50 ×4.07 = 204 km

Is this correct? I am not sure if you can divide the power of battery with power of car.