Longevity question...

[the Spaeth's]

This is going to be one of those hard to answer questions, but here goes
anyway. How long can these things last? More specifically we have a very
nice 91 TQ Avant with 165,000 on it. My wife and I love it and she uses it
for her work commute. It has been very meticulously maintained and has all
of the cool stuff done to it...3" exhaust, chipped, sport seats, euro
lights, 18" wheels, 16" studded Hakka snows, H&R's and adjustable Koni's,
Porsche brakes, new tranny, distributor gear upgrade, a Bernie bar. Anyway
we are trying to decide rather to sell it before the miles get too high and
get her something less fun but with less miles, or just ride it out and
drive it til it quits. We love the car but she commutes at least 60 miles
each way 2-3 times a week at all hours. The vehicle needs to be reliable.
Are we running on borrowed time? If it could be a play car I would definitly
keep it, but this is her main driver. Any opinions?

thanks,
Craig