2017 genesis g80, all wheel drive, 3.8 l engine. car was being driven on a 4 lane expressway in heavy, rush hour traffic using advanced cruise control set near speed limit. g80 was in the left lane attempting to pass a vehicle on the right. there was a vehicle ahead of the g80. driver noticed another vehicle coming up fast from behind until it was very close to the rear of the g80. when driver attempted to accelerate away from tailgating car, engine revved, and did not engage. it appeared disconnected from transmission as if in neutral. tachometer needle swung wildly. vehicle slowed since it was not engaged, creating more risk from tailgater. the tachometer behavior and gear neutrality persisted for approximately five seconds and then engine engaged. took car to dealer who was unable to replicate behavior or detect system errors after three days of work. dealer reported that manufacturer's engineers were unable to recommend anything. no repairs made.