I will try the reverse approach. It is very unlikely that two random vehicles would respond exactly the same over any meaningful distance. There is however more to this than the vehicles. Normally the driver in front ignores those following and maintains his chosen speed by setting his cruse control. Erik sets his and sees his vehicle start to close on the front car so he swings wider on corners to compensate or conversly the other vehicle is faster so Erik cut corners to maintain separation . In efect his "Meat computer" is overriding his cruise control to increase the accuracy. This happens automaticaly with every driver and probably is not noticed it is just experience smoothing the drive. Terry