Abstract: In a vehicle running mode detecting system, a relative speed of a vehicle, equipped with the vehicle running mode detecting system, to a forward object is calculated on the basis of a time elapsed from a reference time based on which the time elapsed is measured and a change in the distance between the vehicle and the forward object during the time elapsed. Whether the vehicle is running in a constant distance mode where the distance between the vehicle and the forward object is kept substantially constant or in a varying distance mode where the vehicle is accelerating or decelerating relative to the forward object and the distance between the vehicle and the forward object is varying is determined on the basis of the change in the distance between the vehicle and the forward object. The reference time is updated less frequently when the vehicle is running in the constant distance mode than when the vehicle is running in the varying distance mode.

Abstract: An energy absorbing structure for a vehicle body side portion, includes a pair of vehicle body members constituting two side portions of a vehicle body, a pair of collision detection sensors for respectively detecting collisions on two side surfaces of the vehicle body, one air bag which is mounted in each vehicle body member, can be unfolded toward the interior of a passenger room, and can receive at least one passenger who is moved sideways by a side collision in an unfolded state, a timing varying unit for changing unfolding timings of the two air bags in accordance with a side-collision direction on the basis of detection results from the collision detection sensors, and an air bag unfolding device for unfolding the air bags in accordance with the unfolding timings set by the timing varying unit.