I hate to be a car geek party pooper, but the Maclaren F1 used wing mirrors from a VW Corrado,
So that story seems a little unlikely
As a Corrado owner, that seems completely believable… they’ll be a special, one-off design fabricated by hand from unicorn horn by Karmann. They will have been obsolete for the last ten years except for one remaining L/H-drive mirror held by VW Classic Parts somewhere in Germany, which won’t fit R/H-drive cars and is priced at £2,500 anyway.
As we live on a road which is apparently a rat-run for the partially sighted and have lost three mirrors between us in two years, I not only fold my mirror in, but I have also invested in the incredibly hard to locate by googling WingAware… which has to be the worst marketed product in history.
It took me two years after seeing one in use to find out what it actually was, viz, a red plastic pointer thing that’s intended to encourage drivers to leave a little more room when passing.