A controller and control method for a motorized vehicle such a wheelchair are provided. The motorized vehicle has at least two driven wheels driven independently by a motor arrangement, and the controller receives a number of input signals from a user input device of the motorized vehicle. The controller comprises drive control circuitry for generating control signals for controlling the driving of the driven wheels by the motor arrangement, the control signals being dependent on the input signals. Speed assist circuitry is responsive to an indication of current consumed in driving the driven wheels to detect occurrence of a loading condition. On detection of occurrence of a loading condition, the speed assist circuitry is then arranged to boost at least one of the input signals in order to boost top speed in the presence of the loading condition. This significantly improves the control of the motorized vehicle in situations where the occurrence of the loading condition may otherwise prevent the vehicle from moving, as for example may occur when seeking to turn the vehicle at low speed.
