Lightweight wheeled surface vehicles of various types and sizes constructed chiefly from commercial off-the-shelf (COTS) parts, incorporate alternate suspensions, e.g. swingarms. One embodiment provides a vehicle incorporating a cellular body design wherein the vehicle is constructed from a varying number of substantially identical cells, assembled end-to-end to produce vehicles of varying size and capacity. Additional embodiments include lightweight passenger vehicles, such as automobiles, manufacturable from COTS parts, including independent suspensions providing large vertical wheel travel. One embodiment provides an automobile-type vehicle having a roll-cage frame, and a lightweight, exo-skeleton external frame, provided in multiple wheel configurations, e.g. three- or four-wheeled configurations. Body panels are quickly and easily attached to the tubular frame and also easily removed and switched and readily replaceable. Bicycles are equipped with electric pedal assist units. Additionally, a pneumatic pedal assist reduces peak power requirements and prolongs battery life.