This paper describes a computer-aided instruction system of automobile driving that is applied when a trainee practices driving with an automobile on a training ground. The system automates the instruction by functions of route guidance and driving data acquisition during driving and by a function of driving diagnosis based on the driving data after driving. The system consists of a personal computer in the control center, on-board computers in automobiles and communication control units connected to the personal computer through GP-IB. Information to an automobile during driving is transmitted over bidirectional, local and digital road-vehicle communication by inductive radio from the communication control unit to the on-board computer. Route guidance information is outputted to a trainee in an aut omobile in a synthesized female voice by ADPCM. Driving data that have been acquired in the on-board computer during driving are transmitted to the personal computer after driving for issue of a driving diagnosis chart. The system has been installed on a training ground and the onboard computers have been mounted in 12 automobiles, For the road-vehicle communication, inductive loop antennas have been buried at 9 points in the roads. Each automobile is equipped with an automatic braking system using an ultrasonic ranging unit for collision avoidance on the training ground. The braking system detects an obstacle within 10m from an automobile and operates the brakes adaptively depending on the velocity. Experiments by trainees show that the instruction system and the route guidance system by speech synthesis are effective on the training ground.