This study proposes an LCA system that provides haptic guidance during lane changes. This system is fully integrated with LKA functionality to provide continuous lateral support during highway driving. Two different system configurations of this LCA are investigated. One is a generalized LCA that provides lane change reference trajectories based on a fixed lane change duration value of 4 seconds. The other is an adaptive LCA that provides personalized lane change reference trajectories through trial-by-trial adaptation to lane change duration of previously driven lane changes. The effects of these systems with respect to mental workload, lateral control performance and user acceptance are investigated. This is observed in an experiment with three different driving sessions for each participant. A manual driving session, a driving session in which the generalized LCA is active and a driving session in which the adaptive LCA is active. The experiments are conducted on a 6 DoF motion-based simulator with 34 participants, driving in a three-lane highway simulation environment with a scripted traffic scenario. To measure mental workload, an auditory cognitive secondary N-back task is introduced. The results show that the introduction of a generalized LCA or adaptive LCA does not have significant influence on mental workload compared to the manual driving session. When the adaptive LCA is introduced, lateral control performance is enhanced compared to the generalized LCA and manual driving. Additionally, user acceptance expressed as subjective usefulness is increased by introducing the adaptive LCA compared to the generalized LCA. Furthermore, inter-driver variability of the lateral control performance during lane changes is reduced by the proposed trial-by-trial adaptive LCA system compared to the generalized LCA system and manual driving.