An object detection apparatus for a vehicle includes a light emitter covered with an emission window, a light receptor covered with a reception window, a defect detection light emitter, a defect detection light receptor and a fracture detection circuit. The light emitter emits a light in front of the vehicle. The light receptor receives the light reflected by an object. The defect detection light emitter emits a detection light into one side of at least one of the emission and reception windows. The defect detection light receptor receives the detection light transmitted through the at least on emission and reception windows at another side. The fracture detection circuit determines whether either of the emission and reception windows are fractured based on the detection light received by the defect detection light receptors.

A collision warning system includes pairs of optical sensors integral to a moving vehicle. Each of the optical sensors of the pairs of said sensors is enabled for the detection of visible light magnitudes and infrared light magnitudes in the external vicinity of the vehicle, and for creating corresponding electrical signals. Temporal changes in the magnitudes of the electrical signals and a probability of a collision with an object external to the vehicle, are determined and a warning signal is generated when collision is possible. Warning information is presented to alert a vehicle operator as to the possible collision. A reference sensor and an object sensor, are enabled for generating the related electrical signals. The reference and object sensors are positioned in such proximity as to determine when a collision object has entered a sensing field of view.

In control apparatus and method for controlling an inter-vehicle distance to another vehicle traveling ahead of the vehicle, an inter-vehicle distance from the vehicle to another vehicle running on a traffic lane at the detected inter-vehicle distance from the vehicle is detected through an inter-vehicle distance detector; a follow-up running control for the vehicle is performed by a vehicular running controller such that the vehicle runs behind the other vehicle, maintaining a predetermined inter-vehicle distance to the other vehicle; and a vehicular velocity variation inhibit command is generated and outputted to the vehicular running controller to maintain a vehicular running state immediately before the inter-vehicle distance detector changes from a first state in which the inter-vehicle distance to the other vehicle is being detected into a second state in which the inter-vehicle distance becomes indetectable is continued for a duration of time until the vehicle passes the traffic lane by the inter-vehicle distance immediately before the inter-vehicle distance detector changes from the first state into the second state.