Just saw 4 degrees on my weather app, guessing we'll probably start having frost etc soon. What should one do to prepare the car for winter ( besides buying Andy's set of winter wheels/tyres http://www.bmwhaus.ie/forum/showthread.php?tid=6629&pid=91715#pid91715 )

Obvious one would probably be to make sure you have windscreen wash that won't freeze, anything else to avoid any potential damage or anything?