Abstract: A drive system for a vehicle having steerable front wheels comprises wheel speed sensors for the front wheels, drive motors for driving the front wheels, and a control unit arranged to receive signals from the sensors, to determine from the signals received by the control unit the speed of the front wheels and the ground speed of the vehicle, and to control the drive motors to increase the drive to the front wheels if the speed of the wheels is less than a desired wheel speed for the determined ground speed, indicating that the steerable wheels are slipping.

Abstract: A vehicle powertrain comprises an internal combustion engine 10 and an electric motor 14 capable of producing driving or braking torque for the vehicle. The exhaust system for the engine 10 includes a catalytic converter 22. A control unit 18 monitors the temperature of the catalytic converter 22 using a sensor 32 and controls the driving or braking torque produced by the electric motor 14 so that the load on the engine produces exhaust gases of a suitable temperature to keep the catalytic converter within its optimum operating temperature range while maintaining the desired total output of torque from the powertrain.