New member from WA - G'Day. Had a 928 in the UK before I emigrated. Just traded in my 05 955 S with air suspension I've had for the last five years for an 09 957 GTS after a long search - this one is a keeper. One owner full dealer history.
Older Cayennes are nothing to be afraid of if you know what you're doing, what you're up for and can find stuff on Rennlist/6speedonline/pelican parts/ECS tuning. But.... and here's the clincher, you must be able to do a little spanner work yourself. Labour rates from people that know the cars and are servicing the vulnerable are extortionate. It's a 150-250k vehicle, parts are not going to be the same price as a 10yr old falcon.
The 957 GTS has a number of differences from the S, it sounds and drives differently, and sounds and drives differently from the turbo too. Basically its a more road orientated car - closer ratios, 295/35 on 21s, more camber, stiffer roll bars, reduced final drive, lowered. The prices for the S and Turbo seem to be continuing down and some bargains are out there - the GTS seems to be bottoming out a little higher than these. Perhaps this is because people think an older normally aspirated donk is less risk than an older turbo. The seats in all of them fit me like a glove so I find them all superb long distance cars. The V8S drives like a big limo (and I think the Turbo drives like a superfast big limo) but to my butt the GTS drives a lot more like a sports car. Think of a 928S2 vs a 928SE if you've ever driven them. The GTS is just a bit sharper.
Powerflex are doing some great poly bushes to correct some of the suspension concerns. The plastic coolant pipes let go on mine and the fix took me 10 hours. Parts were cheap from the UK, but a couple of the pipes were a real PITA to get out of the housings. If I had to do it again I reckon I could it in 6-ish. Everything comes apart and goes back together i.e. no bolts are made of cheese and never encountered a seized bolt yet (did I mention the plastic pipes were a PITA).
There are a few issues that can be addressed by preventative maintenance easily. The driveshaft bush for one - grab some window weld and fill up some of the gaps around the original rubber when you get the car and it won't let go. I didn't do that and went down the vertex carrier route changed in 2 hours. It's easy on a driveway to work on the car because if you fully raise the suspension there' heaps of room under it. Or you can do the 'jimi fix' on Rennlist if you want - but seriously window weld it. And while you're at it put some on the top mount from the engine strut or update it with a powerflex insert. Put some JB weld around the thermostat housing pipes to avoid them backing out if the factory glue fails. All easy DIY stuff to be honest. Drop links are 50 bucks each. Stabilus rear hatch struts are about 200-250 bucks and about 3 hours to fix (research before you do it tho as there is some nasty black glue you don't want to get on the headlining). Keep the drains clear. Use a CTEK battery charger in the lighter socket if you're not driving it. Brakes/Tyres are big and cost a bit too - but are you really going to resent paying for that when you have to stop a fast 2 and a half ton machine in a hurry? Paintwork is superb on the car so with a clay bar and polish they come up a treat. Stainless steel exhaust. Used genuine wheels on gumtree are super cheap and the plentiful 19s with bigger tyres ride better than 22s with rubber bands - but everyone seems to put on 22s? The variable valve solenoids get sticky if they've only had a 15k service interval due to oil varnishes gumming them up. Sounds like a top end piston slap as they tend to stick slighly advanced if they're going to do it. Don't change them initially - do a few oil flushes and changes and actuate the solenoid through both full ranges with a 9v pp3 battery every time it sticks and it'll generally sort itself out.
You can tell I'm a bit of a fan-boy - but honestly the cars are built superbly well, parts and expertise is readily available and if you can navigate the web you can get them at good prices too. Stick your head under the car and look at the size of the anti-roll bar to get an idea of how heavily built these things are. I'm even thinking of getting an old one and putting in some drawers and making a bit of a camper conversion - there a bargain right now and cheaper and much nicer to sit in than a troopy after all.....
Happy to help out on here if anyone has any queries, but browse through Rennlist for the real tech advice. Rich.