I have owned all three makes. My current car is a 01 A6. repair
costs for all are about the same, the difference is in how often they
require repair. Now you can get complaints about every make and model
out there, so you must understand this. here are the cars I have
owned

A6 4.2 (current) 42k miles- no repairs

9-3 Saab Convt. Sold with 39k. bought with 22k, certified. was in
the shop 8 times in 7 months, NONE of these were maintenance related.
the shortest time in service was 4 days, the longest 3.5 weeks.
probably the worst car I have ever owned. when running correct it was
all kinds of fun and a joy to drive. A lemon, no doubt. got rid of
it due to the breakdowns, all of which were covered by warranty, but
totalled over 8k.

BMW 525 sold with 107K, in the shop one time for shocks, and lower
control arms.

Audi 90 Q In the shop three times, once for starter, ignition switch
and another for cat. converter. Sold for the Bimmer, great car
though.

Audi 90 Q. same car as above, never in the shop until an accident at
60 mph in which a car tried to turn in front of me on the hi-way. I
walked away, car was a complete loss.

Saab 900 convt. A/c o-ring replaced at 24k under warranty

So, drive each car, find as much as you can about it both the model
and the specific car. call the VIN into a friendly dealer and they can
help you with repair info. check the car out. any of these can be
great, but as with any car they can also be nightmares. I am probably
the only one on the earth that had a lemon of a honda, so you can
never tell

spinny