There is one on Ebay for a Hyundai Getz with same wheel size and tyre profile but is it interchangeable with an i20? I know someone out there will probably have been through this previously.

Short answer is yes, long(er) answer below!

The specs of the i20 wheel fitment is as follows;

PCD 4 x 100, centre bore 54.1, offset 46( if 2015-2018) or 47 (if 2018 on)

For the Getz;

PCD 4 x 100, centre bore 54.1, offset 46.

(the tiny difference to the offset of the later car, if that is what yours is, will make no difference)

Was there no opportunity no finesse the deal to include up grading the goo to a spare? I got that with my subsequently written off Roomster.

In the dim/distant 20+ years ago after buying a Pug 205 with what was, for some reason, an odd sized spare I had to get a wheel. Peugeot dealer sold me the steel wheel (as were the other 4, it was only an XD) and I then had a fast fit outfit supply and fit a tyre.

Not sure if your comment was directed at me or Concrete, but in terms of what I was relaying, my gen-1 Mazda3 (same with the gen-2, perhaps sans certain top spec models with ICE [CD changer?] in the space) has a space-saver spare wheel and tyre fitted in the underboot area as standard.

The gen-3 does have a space for a space-saver, but the area is not just a circle, it's an odd-shaped cutout and isn't deep enough to accommodate the space saver tyre/wheel that Mazda says to use - hence why the boot 'floor' has to be raised or it has a 'hump' where the tyre is. Mazda does sell the polystyrene cut out, wheel, tyre and tool kit (to go in the centre) but it costs a whopping £395 on the gen-3 car.

It could be the same is the case for the latest gen-4 car - I can't remember. It's a daft situation, given the newer cars are a bit (not much) larger, so you'd think there would be room for the space-saver spare, etc. Mazda dealers (at least in non-pandemic times) might sweeten a deal by adding one for free, but peobably on new cars.

I suspect the same is for most makes in terms of when buying, but not the space issue. I'd certainly push a dealer to include an OEM space-saver spare in any deal if it didn't have one fitted, and I would only buy a car that has a spare and the boot (physical) space isn't compromised to the extent that it can't be used to put the required holiday stuff in there.