The contact owns a 2013 Subaru Impreza. The contact stated while driving at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. The contact stated that the vehicle failed to accelerate above 80 MPH. In addition, the contact stated that the gear shifter did not shift as intended and several unknown warning lights were illuminated. The vehicle was taken to an independent mechanic where it was diagnosed with transmission control system failure. The contact was informed that the torque converter clutch needed to be replaced. The vehicle was not repaired. In addition, the vehicle was taken to the dealer; however, a diagnostic test had not been completed. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 156,000.