You can wash your car but only with water and no soaps, shampoos, cleaning chemicals, was very frustrating
The advice I was given was that between November - March your tyres have to be suitable for the conditions you are driving in. So if driving on a dry day in December with summer tyres you are okay but if you have summer tyres (or not tyres with the snow flake symbol or M+S for mud and snow on the tyre wall) and the conditions are freezing temps, ice or snow and you're pulled you will be fined. You will be fined even more if you cause an obstruction or become stuck or crash and you don't have winter tyres
One of my routes to work was fantastic but could be trechorous in winter and the people rushing to work in the morning without winter tyres were often seen in the ditch. Awesome drive in the dry though
over a wooded winding mountain ridge :)