An articulated seating system supports a user seat using a mounting assembly, a fore-aft slide assembly, a swivel assembly and an extension assembly driven by a drive packet having one or more motors or the like. The seat is moved from a secured drive position (e.g., a standard interior vehicle seat position) to an extension position (wherein the seat faces out of a vehicle doorway) and finally to an access position outside the vehicle, facilitating access for a user having limited mobility, strength, etc. Extendible supporting arms engage and enclose guide rollers to allow stable and precise control of lateral and vertical seat movement. Moving between the drive and extension positions, the seat can move through a narrow transition corridor in the motor vehicle. The motors can operate manually to allow securing the seat in the drive position despite power or other failure.