Take a look at the procedure of the development and engineering of a Formula E electric race car.
Regulations for open development in Formula E are restricted to areas which could potentially solve problems in the world of electric mobility. For these reasons, the primary focus on development within Formula E surrounds the powertrain, rather than focusing on things like the brakes or chassis which aren’t as unique to the sport.
The powertrain consists of a battery pack rated at 28 kilo-watt hours, which sends power to the electric motor. For season one the vehicles used a single motor which was actually the same unit used in the McLaren P1. This motor had highest power density of any automotive electric motor at the time. Traditional motors deliver 2-3 kW of power per kg, while the P1 motor is closer to 8 kW per kg.