A method of quantifying a viscous damping steering feel characteristic of a vehicle equipped with an electric power steering system includes connecting the electric power steering (EPS) system to a rotary actuator and kingpin actuators of a simulator system, communicating a triangle wave control input from a simulator controller to the rotary actuator, and receiving outputs from sensors in the simulator system by the simulator controller in response to the triangle wave control input. The simulator controller is programmed to execute logic embodying a method using the triangle wave control input provided via the rotary actuator and deconvolution of the outputs remove phase lag between the input and output signals, to generate a deconvoluted hysteresis loop for each of a plurality of steering cycles conducted during a vehicle simulation event, and to characterize a viscous damping steering feel characteristic of the EPS system.