The purpose of this paper is to analyse the cooperation between drivers and two simulated Auto-Adaptive Cruise Control (AACC1 and AACC2, respectively, with and without early warning function), which were able to adapt themselves automatically to driving style and to the environment. The AACC1 was presumed to have better know-how (KH) and know-how-to-cooperate (KHC) than AACC2; both were presumed to have better KH and KHC than conventional ACC. The results of our experiment on a driving simulator showed that the improvements in KH and KHC had no influence on the subjective assessments of cooperation and workload; they had a slight positive effect on drivers’ cooperative behaviour. Our results also showed that the more experience the driver had using an ACC, the less the perceived workload was, the more the driver cooperated, and the better his/her assessments of the cooperation were.