A vehicle access seating system comprising a user seat having an axis S, the vehicle access seating system further comprising: an adapter plate having a longitudinal axis A and configured to be affixed to a motor vehicle seat position inside the motor vehicle generally between a motor vehicle transmission tunnel and a motor vehicle B-pillar; a user seat fore-aft slide assembly slidably coupled to the adapter plate and configured to move the user seat linearly in a motor vehicle parallel to the axis A and relative to the adapter plate; a user seat swivel assembly mounted to the fore-aft slide assembly using an off-center swivel post and configured to swivel the user seat relative to the mounting assembly; and a user seat extension/retraction assembly mounted to the swivel assembly and configured to move the user seat linearly parallel to the axis S and relative to the swivel assembly; the fore-aft slide assembly, swivel assembly and extension/retraction assembly configured to move the user seat between an internal drive position in which the motor vehicle can be operated with an occupant in the user seat and an access position that is generally lateral to the drive position and in which the user seat extends at least partially outside the motor vehicle; wherein the user seat, while moving between the drive position and the access position, provides increased legroom for an occupant seated in the user seat by reducing or minimizing the clearance between the user seat and the motor vehicle's B-pillar and by reducing or minimizing the clearance between the user seat and the motor vehicle's transmission; characterized in that the adapter plate is configured to be affixed to the motor vehicle floor pan at a recline angle of approximately 4° to increase the headroom of an occupant in the user seat. an adapter plate having a longitudinal axis A and configured to be affixed to a motor vehicle seat position inside the motor vehicle generally between a motor vehicle transmission tunnel and a motor vehicle B-pillar; a user seat fore-aft slide assembly slidably coupled to the adapter plate and configured to move the user seat linearly in a motor vehicle parallel to the axis A and relative to the adapter plate; a user seat swivel assembly mounted to the fore-aft slide assembly using an off-center swivel post and configured to swivel the user seat relative to the mounting assembly; and a user seat extension/retraction assembly mounted to the swivel assembly and configured to move the user seat linearly parallel to the axis S and relative to the swivel assembly; the fore-aft slide assembly, swivel assembly and extension/retraction assembly configured to move the user seat between an internal drive position in which the motor vehicle can be operated with an occupant in the user seat and an access position that is generally lateral to the drive position and in which the user seat extends at least partially outside the motor vehicle; wherein the user seat, while moving between the drive position and the access position, provides increased legroom for an occupant seated in the user seat by reducing or minimizing the clearance between the user seat and the motor vehicle's B-pillar and by reducing or minimizing the clearance between the user seat and the motor vehicle's transmission; characterized in that the adapter plate is configured to be affixed to the motor vehicle floor pan at a recline angle of approximately 4° to increase the headroom of an occupant in the user seat.