
I currently own a 2003 Porsche 996 Carrera 2, which due to a growing family I really need to swap for something more practical which still has decent performance and is fun to drive. The only options I have come up with so far are the Audi RS6 Avant, or possibly a plain S6 or S4 Avant.
I've never driven an RS6 before, but have a test drive booked of an RS6 for this coming weekend - it will be interesting to see how it compares to the porsche.
In the meantime I have a few questions/concerns, and I would be very grateful if people with more knowledge of these vehicles than me would be able to answer...
First of all, is the RS6 worth the extra money over a basic S6 (which seems to be very rare) or an S4? I reckon an RS6 is about 12-15k more expensive than the latter two for the same age/mileage. How does the tiptronic box in the RS6 compare to, say, a manual S4? (Have to admit I am getting lazier as I get older, and a tiptronic quite appeals nowadays).
The car I am test-driving is the dealers demonstrator, is also for sale, and it seems to fit my spec - avant with a low mileage on a late plate, with nice subtle grey-metallic paintwork. However I am a bit wary about buying an ex-demonstrator, as I expect it's been thrashed from new. What's the running-in procedure for these cars - is it likely to have come to any longterm harm if driven hard from new?
I understand that the sat-nav system was updated from a CD-based one to DVD-based. When did this changeover occur? I drive a fair bit in Europe, and would prefer to avoid the expense and inconvenience of buying and carrying around extra disks.
The dimensions of the RS6 make it quite a bit bigger than my 911 which fits in my garage. It's unlikely to get damaged on my drive in the area that I live in, but at the back of my mind is the thought of an aggravated burglary for the keys if it's just sitting there on the drive visible to all (with small children in the house, it's the last things I want). I'd really be interested in getting a feel for how big a theft target the car is, and whether it would be worth getting it debadged.
I'm probably going to lose a lot of money on the 911 if I trade it in at an Audi main-dealer, as all they'll do is phone around in the trade to get a bottom-line price on the 911. On top of that I'll end up paying top-whack for an RS6 from a main dealer. Does anyone know of any reputable independents or other dealers who perhaps deal with both types of car and may be able to cut me a better deal?
Depreciation? At the moment I intend to keep the car for some time...but then I always say that, and typically keep a car for only 1-2 years. How well will they hold their value? Particularly with the new A6 just come out.
Finally are there any known serious faults with the cars...on a par with say the oil leaks and engine problems on early 996's which meant a number of engine replacements?
Thanks in advance for any help/advice on these points

Gary.