A car seat is configured to rest on a vehicle seat and to support a child. The car seat has a shell with a front side, a rear side, a seat back end, a seat bottom end, and a seating surface with a seat back portion and a seat bottom portion. A first contact surface is defined on a part of the car seat facing generally opposite the seat bottom portion. Adapter bodies are carried on the car seat. Each adapter body defines a second contact surface and is movable between a stowed position in which the first contact surface is exposed and positioned to rest on the vehicle seat with the seating surface at a first incline and a deployed position in which second contact surfaces are exposed and positioned to rest on the vehicle seat with the seating surface at a second incline different than the first incline.