This article presents an optimal design of an exterior permanent magnet (PM) tubular machine for energy harvesting from vehicles suspension systems. By using a hybrid structure, in which, the mechanical damper remains and electrical components are attached to the damper's frame, the damping force and damping coefficient are still ensured while wasted kinetic energy is recovered. To maintain driving comfort and safety, the detent force and electromagnetic force must be minimized. The constraints for dimensions of the exterior PM tubular machine were obtained from an actual shock absorber from a school bus, a large-size vehicle. Different topologies were investigated to maximize the output power and power density, while the electromagnetic force was minimized and negative effects of the initial positions to the machine's performance were mitigated. Finite element analysis showed that maximum and average power from an optimal design were about 210.2 and 103.7 W, respectively. To verify the validity of the design, a prototype was fabricated and tested.