The contact owns a 2015 Nissan Sentra. The contact stated while driving at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. In addition, the transmission was slipping. The vehicle was taken to an independent mechanic where it was diagnosed with transmission failure. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 83,000.