The Toyota Prisus' transmission is much more fascinating then you might think.

A constant velocity transmission or and a traditional transmission increases the gear ratio at lower speeds to allow the wheels to turn a smaller distance in comparison to the engine speed. This provides more torque to wheels help the engine overcome inertia of the car at low speeds.

The Prisus takes a different tack. The engine operates at a constant gear ratio, but to provide the additional torque needed to get the vehicle moving at low speed, it uses an electric motor to assist the gas motor at spinning the wheels.

It's a very cool concept!