The contact owns a 2018 Toyota Prius. The contact stated that while in bumper-to-bumper traffic, the vehicle suddenly accelerated. The brake pedal was applied but failed to respond. The driver crashed into the front passenger side of the Lexus. The vehicle continuously moved forward. The contact was eventually able to pull over safely. The pre-collision malfunction warning light illuminated. The brake malfunction light was flashing. The air bags did not deploy. There was no reported fire or injury. A police report was filed. The vehicle was taken to the local dealer, who could not determine the failure. The vehicle was not diagnosed or repaired. The vehicle was then towed to an autobody center where it remained. The manufacturer was contacted, but no additional assistance was provided. The approximate failure mileage was 39,000.