Abstract: A modular seat loading system for loading of various driver seats onto an off-road vehicle (ORV), forming a modular wheelchair-accessible ORV. The modular system includes controllable length-adjustment devices, configured to controllably adjust angular position of a floor of the ORV, by controlling length thereof, for switch ably achieving ORV modes: a load mode in which a floor structure of the ORV is tilted forming a non-zero angle ??????? the ORV floor and a ground surface, for removably loading a wheelchair or a wheel-less seat for serving as a driver seat; and a drive mode in which the ORV floor structure is lifted from the ground. The modular seat loading system also includes a load controller configured at least for adjusting length of the length-adjustment devices. Each of the length-adjustment devices is also configured and used for movement suspension of the ORV by enabling natural expansion and contraction responsive to ORV movements and road conditions.