my wife drives a 98 a4 2.8l avant quatrro with 135000 miles on it, she loves the car and I can't get her to trade it for anything. It has been a good car since new, yes, the timing belt has been changed and the front control arms have been replaced(audi paid for the arms) and yes, the abs module was repaired. The 30v 6 is a smooth motor and the only issue I have is that the cam covers are prone to leak, bad design.
My daily driver is a 00 a4 1.8t quatrro, it has 60000 miles on it and drives fine, knock on wood, no issues yet. At 75000 will change the timing belt. It seems peppy enough but is ain't my porsche