A method for controlling a mild hybrid vehicle is disclosed. The method includes: controlling a multi-point injection (MPI) fuel system for supplying fuel to an engine for a low revolutions-per-minute (RPM) operation; subsequently, causing a gasoline direct injection (GDI) fuel system for a high RPM operation; switching to the multi-point injection fuel system when it is determined that the gasoline direct injection fuel system fails. The method further comprises calculating a torque deficiency due to the switching from the GDI fuel system to the MPI fuel system and controlling a starter-generator to generate an assist torque to compensate the torque deficiency.