A mounting system for an electric vehicle includes a front cross beam extending from a right side of a passenger compartment of the electric vehicle to a left side of the passenger compartment. The mounting system includes a rear cross beam extending from the right side to the left side. An underside of each of the front cross beam and the rear cross beam defines a plurality of mounting features configured for mounting a battery assembly to an underside of the electric vehicle. A plurality of seat rails extend across and mounted to the front cross beam and the rear cross beam, the plurality of seat rails being configured for mounting seats within the passenger compartment.