Speed controller selection help

I am a mechanical engineer and now I teach technology at high school. We are going to construct a car moving with photovoltaics using the solar radiation. The data are: 2No. photovoltaics each 165 W, 4 No. batteries each 12V connected in series, a d.c.motor 48V. The question is to find the proper speed controller to be used for forwarding and reversing the car. The car weight excluding batteries and the motor is 400Kg. The speed controller is going to be used in cooperation with the accelerator pedal. Is it possible to send us some tech info regarding the model, price, wiring diagram of the speed controller and any other technical info.

Please check the instruction manual of our controller AX2550. It explains in great detail how to use the controller. In particular you may want to note two sections:
1 - open loop speed control for the wheels
2 - closed loop position control for accelerator and steering wheel.
Our controllers operate on a three 12 Volt battery system (36 volt)