A vehicle control system reduces the arithmetic operations for deciding the passableness of the vehicle through an upcoming curve and also avoids unnecessarily effecting automatic deceleration and warning, which are not completely indispensable in a system for performing the warning or automatic deceleration, so that the vehicle may pass through a curve at a proper vehicle speed and with minimum distraction to the vehicle occupants. Assuming that the driver performs a voluntary deceleration at a predetermined deceleration from the current vehicle speed, the system calculates an estimated passage speed of a tentative position N.sub.k, as set on a road ahead of an actual position P.sub.0. The system then sets a passable zone Z.sub.1, a warning zone Z.sub.2 and an automatic deceleration zone Z.sub.3 on the basis of turnable radii R.sub.1 and R.sub.2, at which a predetermined transverse acceleration is established at the estimated passage speed, as well as an arc C.sub.1 ' defining a range of a predetermined distance from the tentative position N.sub.k. The driver is warned by the system, when any of nodes N.sub.k+1, - - - , and soon ahead of the tentative position N.sub.k is present in the warning zone Z.sub.2, and the vehicle is automatically decelerated by the system when any of the nodes is present in the automatic deceleration zone Z.sub.3.