[200q20v] V8 vs old S4/S6 in reliability and handling

[Lawrence C Katzenstein]

Hi,
   I've had a V8 for about 4 years. It has cost a fortune to bring up to
specs- new heads, various new sensors, new UFO brake pads, various tanks
like for the windshield sprayer, a recent new steering rack etc. The worst
part of this is that I am now quite fond of the car since it is running
the way it was supposed to, but initially I found it heavy and
awkward. Before my V8 I had had a Nissan Maxima SE 5spd for 200,000
miles. It looked great, was fast, got good to great gas mileage, and was
bulletproof in reliability. The V8 is slower off the line, but faster at
the top end. It also looks a little too much like an old Audi 5000 which I
liked but didn't love. It actually alters the old 5000  look enough so
that I really like
the V8 but prefer the looks of the newer 100 and A6 if not the even newer
fastback. 
  Is there any reason I should stay in a V8 if I can pick up an old S4 in
terms of appearance, room, 0-60 acceleration, top end, safety or seat
comfort? I do love the support of the V8's seats on long trips, but
imagine that the S4s are similar. Why would a turbo 5cylinder move faster
than a plain V8? Does the hot air from the turbo reduce engine life? 
  I'm sure others have gone over this before, but I haven't. It sure would
be nice to have a faster, sleeker, more modern version of what I have now
with even better gas mileage, but I sure don't want to start over with
another difficult and expensive car to repair. If the cars are really
similar I'll just stay put and put the extra money in the bank.
Thanks,
Larry