Vehicle speed control system and method for limiting the rate of acceleration when changing from a first target speed to a second one due to a request from the accelerator pedal

A speed control system for a motor vehicle, the speed control system comprising:

• an accelerator pedal displaceable by a driver to indicate a driver drive demand via displacement of the accelerator pedal;
• and
• a processor in communication with the accelerator pedal, the processor configured to cause automatic operation of the vehicle in accordance with a first target speed value stored by the system at least in part by controlling automatically an amount of drive torque applied to one or more wheels by a powertrain, the processor being configured to receive an instantaneous driver drive demand signal in response to a prevailing driver displacement of the accelerator pedal;
• and
• wherein the processor is configured to determine a second target speed value greater than the first target speed value in dependence on the instantaneous driver drive demand signal;
• the processor being further configured to cause automatic acceleration of the vehicle from the first target speed value to the second target speed value in accordance with the instantaneous driver drive demand signal and at a rate not exceeding a maximum rate of acceleration;
• wherein the processor is configured to cause the second target speed value gradually to become equal to the first target speed value when the instantaneous driver demand signal corresponds to an amount of drive torque substantially equal to or less than that required by the system to cause the vehicle to operate in accordance with the first target speed value.