I owned a 1995 Audi 90q and it was more trouble than it was worth…leaked/burned oil and had many problems with the wiring. As the Audi tech told me, older Audi’s (early to mid 90’s) had horrible electrical problems because Audi made most of their systems way too sensitive.
The car was great to drive and that’s why I bought it. Hopefully some more people will chime in, but there were certain years that were troublesome for A4’s so you just need to avoid those. However, a newer Audi may not have as many problems and might be a blast to own.
On the flipside of this, you will always find those die-hards that say they’ve had their car for 200k miles with no major faults.