A method for modeling an Electrorheological (ER) damper is proposed. The modeling method comprehends two simple steps: characterization and model customization. These steps are based on the experimental data of the damper behavior. Experiments were designed to explore the nonlinear behavior of the damper at different frequencies and actuation signals (i.e., automotive domain). The resulting model has low computational complexity. The method was experimentally validated with a commercial damper. The error-to-signal Ratio (ESR) performance index was used to evaluate the model accuracy. The results were quantitatively compared with two well-known ER damper models: the Choi parametric model and the Eyring-plastic model. The new proposed model has a 44% better ESR index than the Choi parametric model and 28% for the Eyring-plastic model. A qualitative comparison based on density plots highlights the advantages of this proposal.