Methods and system for improving hybrid vehicle efficiency

A hybrid powertrain operating method, comprising:

• in response to a first requested engine power trajectory based on an accelerator pedal position progression, transitioning engine operating conditions between a first engine fuel consumption operating region of an engine brake specific fuel consumption (BSFC) map and a second engine fuel consumption operating region of the BSFC man in a first amount of time, the first engine fuel consumption operating region separated from the second engine fuel consumption operating region via engine speed and torque, where an engine consumes fuel in the first and second engine fuel consumption operating regions at an equal rate, and where a third engine fuel consumption operating region of the BSFC map exists in an engine speed and torque region between the engine speed and torque regions of the first and second engine fuel consumption operating regions, wherein the first and second engine fuel consumption operating regions are completely separated by the third engine fuel consumption operating region;
• in response to a second requested engine power trajectory based on the accelerator pedal position progression, transitioning engine operating conditions between the first engine fuel consumption operating region and the second engine fuel consumption operating region in a second amount of time;
• and
• adjusting operation of a motor to provide a desired powertrain torque when transitioning engine operating conditions between the first and second engine fuel consumption operating regions.