At the end of the day they are glass so would need some antifreeze/screen wash liquid in there to stop it freezing and cracking thats what happened to them. Or Take it inside wrap it in bubble wrap, in a box, more bubble wrap, in another box then write fragile on it then put it in the roof for next 25 years then sell it Just put it away safe for now as not worth the frost risk then get it out nexy spring!
Proud owner of 2 british built boxes of motoring fun filled brilliance!! Daily driver: 1989 Standard Mayfair 998 Auto Current project: 1961 Morris Deluxe - Will be roadworthy unrestored 61.... http://mini-hawcs.com/