There is one spare part that should always be carried in the car, a DME relay. It plugs in next to the ECU under the passenger seat on my car and provides power to the fuel pump. The DME relay can stop working for no apparent reason and it’s the first thing to check should the car refuse to start. In the 12 years I have owned the car, the DME has only let me down once and that was in the 12th year. I turned the key and was stunned to hear the starter motor cranking the engine, but the engine refusing to start. A quick change of the relay and once again, the car started first turn of the key. One thing to add, a torch would come in very handy, should this happen at night.
Over the years I have bought all sorts of spares, some new, some used, some refurbished and some the ever popular new old stock. I even have a spare set of wheels, spare brake callipers, fuel pump, flexi oil pipes, windscreen wiper arms, etc etc.
Quite a few parts are no longer made, but there is no shortage of Porsche breakers in the UK and all over the world, so keeping cars like mine and a lot older on the road isn’t too difficult if you know where to look. Porsche has responded to the classic parts supply, they now have a new string to their bow, and they have reintroduced quite a few parts for their classic cars.