The contact owns a 2019 Lexus RX350. The contact stated that while driving at 70 MPH with the cruise control activated; the forward collision avoidance feature failed to operate as needed. As a result, the contact hit an 18-wheeler vehicle that had unexpectedly merged into his lane. The contact depressed the brake pedal prior to the collision back of the vehicle at approximately 10 to 15 MPH. The air bags did not deploy upon impact. There were no injuries and a police report was not filed. The contact managed to still drive despite minor front-end damage to the vehicle. The contact took the vehicle to the dealer where it remained in their possession for three months; an investigator was sent to the dealer to inspect the vehicle. The investigation determined that there was no fault with the vehicle. The manufacturer was notified of the failure. The vehicle had yet to be repaired. The failure mileage was approximately 9,000. The contact stated that the radar assisted cruise control nor the brakes helped to slow the vehicle.