fwiw, I have a set of Dunlop Winter tyres for my TT quattro; it sticks like snot to an oven door on the "normal" tyres but on the Winter tyres it can squirm around a fair bit. They only work when the temperature is at it's lower limits for the UK- which is perhaps not a surprise. They have much less grip in the wet than the "normal" tyres no matter what the temperature. Unless global warming makes us have really cold Winters
or you live in a remote snowy place, I don't think they are essential in the UK. I really only bought mine to save my very fancy wheels from being ruined by salt.
I would not even consider buying any for an Elan.