At a speed of 50-70mph, there is very violent vibration that shakes the whole vehicle and the occupants, including the steering wheel, pedals, and the the seats. It gives an impression of running over very rough surface in spite of very smooth road surface. The vehicle seem to undergo both vertical and horizontal oscillation. I have undertaken wheel balancing severally, and even had all the 4 tires changed. It has made driving the car an awful experience, and I have in fact stopped driving the car entirely.