Regarding your suggesting of run-flats being a viable alternative to 'space savers', I would have to suggest a caveat is required. It is my understanding it is 'impossible' to repair a run flat once it has been punctured. Taking this into account, given that run-flats are typically more expensive to buy in the first place, and that you will always need a new one after a experiencing a puncture, it appears is a very expensive solution to what is essentially a minor risk of the small inconvenience of travelling at 50mph for 100 miles. I tend not to think of the spare as a 'space saver' because, as B.J. mentions, it actually saves no space in the wheel well, but rather as a 'get you home' facility until you are able to get the tyre repaired or replaced. I agree with B.J.'s cynicism regarding manufacturers attempting to keep costs down in an attempt to maximise margins and profits, as a number of manufacturers are no longer providing a spare of any description, but rather the car is issued with a can of what is essentially expanding foam to re-inflate the tyre. I wonder how this works if one suffers a blow out? My guess is that it doesn't.