Range estimation for electric vehicles (EVs) is an important point to have carefree use. Motor loss parameters are required to estimate the range of EVs. However, many electric motor manufacturers do not provide these parameters without special permissions. Besides, at the design stage of EV, many motor alternatives must be considered. This complicates the permission process as there are several suppliers to deal with. Instead of these parameters, torque-speed curve and efficiency map are presented in the electric motor datasheets. This paper presents a novel range estimation method that uses efficiency map instead of motor parameters to calculate the motor losses. To validate the proposed method, both simulation and experimental studies are carried out on a midi-bus. Furthermore, the effect of different battery capacities on the range of a heavy electric vehicle is examined.