Abstract: A system, method and computer program for simulating vehicle energy use is provided. Drive cycle data collected during real-world driving of at least one vehicle is received by at least one computing device, and engine torque information associated with the real-world driving of the at least one vehicle is also received. Vehicle payload mass of the at least one vehicle is estimated based at least partly on the respective received engine torque information, and energy use of the at least one vehicle is estimated based at least partly on the respective drive cycle data, the respective torque information, and the estimated vehicle payload mass.