I bought mitsubishi mirage in April. Recently I heard very minor noise and a small jerk on accelerator when car is driven from cold state. Its always heard at fixed speed of 40 kmph and just once; till the car is parked again. Even if I keep driving it for one hour and car stops in between accelerates from speed zero many times then neither I hear any sound nor I observed any jerk on accelerator. Once while using reverse gear I felt grinding minor impact on accelerator in inclined drive. Any suggestions? What can it be. And what is making noise heard only once when car starts from cold state and at fix speed. Is it cvt or else. Cvt fluid is as clean as it can be. Car is just 26k driven. I usually don't drive more than 80kmph speed.