I have a 99 A6 Avant that has developed a shaking in the steering wheel and the car at high speeds. It starts around 50-60 and reaches its peak around 70-75 (I can go faster than that and it just pretty much stays at the same intensity level). I have taken it to my mechanic (who frequently works on Audis and is also a family member so is trustworthy) repeatedly and have had a regular balancing, high speed balancing, and a four wheel alignment performed. The problem has become slightly less intense, but not significantly. There are 4 new tires on the car with less than 10000 miles on them.
I don't know if it's related, but the car also has a mysterious pulsating when the wheel is turned sharply.
Any suggestions for either problem (the high speed vibrating or the pulsating while turning) would be greatly appreciated. I read something about a Hunter road force test in another post, but am not sure if it applies to this situation or not. Thanks!