When learning to drive and with practice the driver's task becames increasingly automatized and requires less resources and gradually appears effortless, safe, and easy, providing drivers at the wheel with more time to be used for both traffic and non traffic activities. So does automated, intellignet driver support, too. This paper first considers differential effects of this development on drivers' attention control time sharing needs and possibilities at the wheel. Secondly, it deals with the reference model to be used in intelligent driver support, and posits a close relationship between the concepts of time safety margins and mental load in driver behavior. Last, this paper asks whether driver support should be adaptive with respect to different drivers.