Before the car is warmed up, when you accelerate, the transmission wouldn't shift to a higher gear smoothly. The car rumbles and then when you let go of the pedal, it'll return to normal. The only way to get around it is a slow acceleration, but that is difficult when you have to accelerate fast onto traffic. Many times the car stalls right after I start the car accelerating into traffic. It also makes a noise that sounds like the engine is being taxed. This happened 4 months after purchase of a brand new car and a dealer service repair of a leaky transfer case. When it is cold, it also whines at the acceleration. All of this goes away when the car warms up about after 10 mins.