The contact owns a 2020 Land Rover Discovery Sport. The contact stated while driving at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. The vehicle independently decelerated and lost motive power. In addition, the check engine warning light was illuminated. The vehicle was not diagnosed or repaired by an independent mechanic or the dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 81,000.