Most Porsche 911s (and some other models) come with a spacesaver spare wheel which is stored with the tyre deflated. To use it, then, you have to blow up the tyre and, to that end, Porsche supplied 911s with an electric tyre compressor that plugs into the cigarette lighter. This is also handy for topping up the air in the normal tyres.
The original tyre compressor came in a variety of styles over the years; the photo below is a Porsche 964 compressor and it’s a smart piece of kit. It’s housed in a plastic box which opens to reveal the electrical lead and plug, plus the pipe that attaches to the tyre valve. There’s also the compressor unit itself and a pressure gauge, both of which remain in the case during use. All very smart but Porsche obviously didn’t make any concessions to size or weight saving when designing this. Later compressors were smaller but less impressive.
Annoyingly, in many cases, we find the original tyre compressor to be missing and replaced by a generic item from, say, Halfords. I’ve never been too sure why this would be – do people keep them in their garage and forget to pass them on to the car’s next owner? I know sometimes they do stop working – probably due to corrosion (boots can be damp places) and lack of use.
And what about that spacesaver wheel? They’re a mystery to most people and on the rare occasion you have to use one, you have the interesting challenge of what to do with the full-size wheel you take off – the rears especially are big! I was pleased to find a video of a Porsche spacesaver tyre being inflated – it looks an old example that I wouldn’t want to trust on my car but it’s interesting to see the process, nonetheless.