ChemEJon
Member
Porsche Taycan.
The use of a 2 speed transmission is probably to account for the constant torque region which from what I've seen is around 50-60 mph. Below is a operational curve for an ac motor.
By having a second gear ratio, you can effectively reduce the motors angular velocity or RPM allowing you to increase the maximum wheel speed of the vehicle while staying in the constant torque region.
This is just some speculation, it may or may not be 100% correct.