This paper proposes a new concept towards the understanding of seating comfort. Physical comfort is defined as the physiological and psychological state perceived during the autonomic process of relieving physical discomfort and achieving corporeal homeostasis. In addition to static and dynamic comfort in an automotive seat, the occupant will also experience transient comfort. This is the comfort perceived during posture change or fidgeting on the seat. It may depend most on the material properties if posture requirements are satisfied. Lumbar support is exemplified to illustrate this concept. New seat comfort evaluation tools should be developed to account for the transient properties of the seal supporting system.