For horror stories, then it seems pretty quiet (but most cars do not do many mile per year).
The turbo was an evolution of the GT1 engine, with water cooled cylinders (since the GT1 had water cooled heads, as did the 959), and the gearbox was an evolution of the 993 GT2s.
Most items were proven so there was minimum risk.
The normally aspirated cars (aside from from the GT3) were a whole new design.
Here is some consolidated info I have mentioned to others before (there are some comments in PCCB, since I was asked - GT3 people may disagree):
The 996 turbo only ever came in one external appearance. The modified headlights were adopted by the other models in the range. So there is no pre/post facelift version.In terms of external appearance, it makes no difference what age of car you purchase.
PCCB (Porsche Ceramic Composite Brakes) were only an option on the turbo, apart from the end of life turbo S (where they were standard). They were not available from launch, so will not be fitted to the early cars. I do not think they are a very common option to have been fitted.
You read various stories about PCCB, I have spoken to a couple of Porsche driving instructors about how reliable they are (since I was wondering about them myself). The official line is that there was never a problem. However, it should be noted that they have recently changed the design and modified the cooling ducts, although this is claimed to part of normal product improvement, and should not be considered to represent an admission there was anything wrong before. I was told Porsche have spent some time with a couple of people that have suffered premature failures. They have found that the people are barking too hard, for too long, i.e. bad driving technique. This is putting excessive strain on the brakes and they are overheating. Once given some instruction, they claim there should not be a problem. One of the benefits of ceramic brakes is the lack of fade, but this is also means there is little indication to the driver they are using them too hard. Personally, I am not quite sure where the truth lies.
The performance of the steel discs is perfectly capable. The main advantage of PCCB is the reduction in unsprung weight, but unless you are very good and you lower and stiffen the car to fully take advantage of the handling, then I do not think it makes enough of a difference. Basically, I consider brakes to be a consumable. The PCCB option is just too expensive come replacement.
I decided that if there was a doubt in my mind, I would not brake as had or worry about them, which would reduce the enjoyment of the car. So I will stick with the steel discs. There is an additional benefit to PCCB, which is that they do not rust. My car lives outside, so the brakes corrode a bit. But I use it everyday, so it is not a problem. However, some people have had problems with the inner face of the rear discs corroding, although this is avoidable given some care and regular usage.
Maintenance is down to mileage rather than age, and previous usage. At 3 - 3.5 years old, nothing much should need replacing (unless high mileage, then maybe the shock absorbers). The biggest unknown with a used car is what the previous owner did to it.
I do not know what to say on this. But if you buy from an OPC you should be fairly safe, but get an inspection anyway. I suspect private sellers may not let you drive it, so it could be hard to tell.
In general though, the turbo is pretty strong. I would look for one that has been used, rather than one with very low miles. According to my OPC, they reckon low mileage cars have more issues. Absolutely 100% get the extended warranty. It costs £725 or 750 (I can't remember exactly) per year. It the same as for a C2 or C4, which is very good value. A new gearbox is around £5K, and a new engine up to £18K, so if one of these breaks it would be bad. The warranty can be extended to 120K miles or 9 years, but does not cover suspension parts. Additionally, the warranty covers you for breakdown, which includes a replacement car (BMW or Merc) while they fix your car. £200 of the price is for the breakdown cover.
I have done 25K in mine (in 18 months). First service at 12K was £350, second service at 24K was £1100 (spark plugs were changed). The brake fluid was not changed, since it needs to be done at 24 months, so I will get it at the next service. 36K should be about £350 I expect (plus brake fluid), then there is the big service at 48K, which will be more since the polyrib belt needs to be changed and the fuel filter changed.
If you do less mileage, then the minor service should be done after 2, 6, 10... years, major service done after 4, 8 12... years. Should you drive it a lot, then the transmission oil is changed at 96K miles and front diff oil too. Every 2 years you get a free condition report, which is necessry for the Long Life Guarantee. I have had to replace the 3rd brakelight since mine cracked for some unknown reason (about £50 plus VAT). Also a new set of tyres, £630 from Micheldever.
I do not eat tyres, since most of my mileage is on motorways.
You might also like to know that there was an engine upgrade (X50 option) which was not available from launch and cost 8.5K. It upped the power from 420 to 450bhp and torque from 560 to 620 Nm. It does make a noticeable difference. The reason for mentioning this, is that the gearbox is strengthed on the X50 cars. My car wines a bit, especially under full power, and it seems OK, so some transmission noise may not be a problem.
The clutch feels odd, since there is no cable but a hydraulic cylinder with a servo. This is correct operation. You will also stall it in reverse, this is also normal.
I personally do not like the tiptronic system, but this is personal choice. You can't mess up gearchanges with it and in the real world is easier to drive fast. But it is down one gear ratio (only 5 instead of 6) and is heavier, thirstier and slower.
On the later cars, just about everything was included. On the early cars there was more scope.
I reckon the embossed crested headrests are essential. I think the BOSE stereo was standard apart from the first car.
The sunroof was standard on the later cars, but it is not that important.
The aerokit is not that practical, since you will scrape the front lip. At least on the standard car it is not painted, does not jut out as much and is cheap to replace. The rear wing is not that attractive to my eyes, so I would avoid the bodykit, or not pay extra for it.
Heated seats are nice to have in the cold weather. Stainless steel door guards are a nice touch.
The most important interior item is the handbrake and gearlever in alumimium which gives you a chunkier gearlever and a metal insert in the handbrake with Turbo written on it. It lifts the interior.
The sat nav is nice to have, although obsolete, so will become more out of date. However, the screen integrates all the functions together nicely.
The rain sensor for the wiper is nice, but not essential, although the electriclly dimming mirrors are useful (note that only the drivers side dims, not the passenger side, which is annoying).
I have a short shifter, which I like a lot, although it was only available in the last 12-18 months of production (but can be bought aftermarket).
All the other interior trimmings are personal taste items, so I would not worry about them.
Sensible colours are easier to sell on of course.
For the interior, I am sure the metropole blue looks best and is nicest to live with, but almost no-one specifies it.
The standard electric seats are fine, although I prefer the sports seats. They have little winglets by your shoulders, and slightly deeper bolsters. The sports seats lose the electric fore/aft movement (which saves quite a lot of weight) and means sliding the seat forwards and backwards is a lot quicker for rear access. Although you then can't just press a button to get the seat back to position after servicing.
I would not get a roll cage and bucket seats or harnesses, since this will limit the appeal to others. People who are that hardcore will buy a GT3 or GT2.
At the moment many expensive cars are seeing their prices drop (Lamborghini, Porsche, Bentley, etc.). Even the OPC prices are generally less than they were. You can look at the OPCs, or the Porsche independents or even magazines and the Sunday times for cars.
The X50 cars do seem to be a little more desirable, since they can be tuned more (although it will invalidate the warranty).
Once 997TT deliveries start, you may see some additional cars, although you may have to wait 9 months for that
As an everyday roadcar, it is probably the best thing you can buy.
I drove 500 miles and 11 hours in the snow and ice 2 weeks ago, and it is fantastic. Whether the weather is good or bad, it is a great car to be driving about in - probably the finest way to get 1 or 2 people plus luggage (within reason) around quickly, in comfort and safely (plus reliably - touch wood).
The main thing is the way it feels small on the road, the fantastic visibility (there is no bonnet in the way), the communicative controls and the performance.
If you are not used to turbos, then the driving experience and technique is quite different to normally aspirated cars. I love them, but there are others that don't get on with them. You need to use the mid range torque - 3000-6000 rpm is where you should be, then it is all there to be used. It is more relaxed.
You can go completely mental, but actually driving at 50%, shifting quite early, will make almost as swift progress.
If you get a test drive, then do what I was advised, put it in 2nd and 3000 rpm (if the road is dryish) and floor the throttle, change up and floor it again. You will go from 40 to 100 in about 5.5 secs in an X50 car, or around 6 in the 420bhp version. You will be pushed into the seat in a way the normally aspirated cars just don't, and the turbo wooshing sound is great. The only problem is there are not enough straight roads and there are other people driving about, so you can't do it very often.
I bought mine intending to keep it for a long time (10 years+). I bought new so I could spec it. So far I am still of the opinion it was worth the money, and I still think I could just manage to keep it that long without being tempted away.
Another little trick you might like to know about, when they service the cars, they can reset the ECU. Since it learns over time how you drive, it ends up become more sluggish. Most of the time on our congested roads with their slow limits and dawdling drivers, it is hard to really get your foot down. So the engine management backs off the boost since you do not need it. This means it takes a little longer to get full power and the response is a little less sharp. If the battery is disconnected, then I think it resets. Certainly after being serviced it feels sharper and I get more boost more easily.
Run it on Optimax or BP 97 octane, these seem best. BP subjectively gives more power at the top end, Optimax more torque, but I could be imagining it.
You also get more power on cold damp days.
The traction control and stability control is backed off a bit from the other cars - you can spin the wheels and get a few degrees of slide before it intervenes, which is more fun.
Opinions on tyres vary, but I use the Bridgestones. The driving instructors (who use a set a week) reckon they break away more predictably which allows you to push harder with more confidence. Many rave about the Pirellis, but I have found the limit harder to judge (although on other cars). The Continentals are pretty reasonable and have a good rim protector.