I have a 2001 Jetta 2.0 automatic the speedometer needle will begin bouncing when the speed is above 70 mph. The needle will move up and down about 3 MPH. If the cruise control is on, the apparent speed fluctuation will cause the cruise to go crazy, trying to respond to the apparent speed changes. If traffic slows below 70, the bouncing stops. Sometimes it comes back right away above 70, and sometimes it does not. The bouncing or fluctuations do not occur while driving around town. Only when at a constant speed at or above 70 for several miles.