Controlling an engine start of a hybrid vehicle

A control system for controlling an engine start of a hybrid vehicle having a powertrain system comprising an electric traction motor and an engine with a starter motor, the control system comprising one or more processors, the one or more processors collectively configured to:

• receive a first input signal indicating that a vehicle mode has been selected in which the use of the electric traction motor as a sole source of motive power is prioritised;
• receive a power demand signal indicative of a power request;
• receive an engine start signal indicating that an engine start is required;
• determine, in dependence on the power demand signal and engine start signal, whether the power request is below a power threshold of the electric traction motor;
• and
• output a control signal to the powertrain system to perform the engine start using the starter motor if the power request exceeds the power threshold, and to perform the engine start using the electric traction motor if the power request is below the power threshold.