Just to give you a laugh - I have someone I know who makes custom carpets so I had a set made for the Spider.
Now the factory attention to detail is not that great such - they made the first square set that slide under the seat the wrong way round (so the logos would be at the side) and also in a different carpet to the fronts. They improved with the second set in as much as the logos were sort of in the right place but again used the wrong carpet. It was only the third set he finally got right!
What that means is I have 2 sets of carpets that fit perfectly under the seats if anyone is daft enough to add carpets to their Spider - I can obviously get matching footwell carpets if required. I believe they top quality wool with leather edge and are something like 55cm wide by 53cm deep.
They are too good to throw away and would actually cost you a significant amount to buy.
Anyone interested before I use them in the garage.