Thanks for all the responses. The law is different in Finland indeed - unfortunately towards wrong direction. Here you can have back seat windows and rear windows completely non-transparent if you like, but front and the windshield is another story. You actually can tint them aswell very slightly, but the
problem is that it is illegal to apply any film to them - so only way to tint them legally is to use darker glass itself -> it is too expensive for the effect.
But what I want to do is to tint the back windows a bit more. I have 80% tints on my wife's A3 and it looks perfect on a black car and it has also nice effects other than just the look - when parking to a sunny spot, turning the rear towards the sun will keep the car much cooler inside since quality films will drastically reduce the sunrays effect. Also, it's much nicer for our child to travel on the child seat on the back, when he is much less dazzled from the sun. Yes, I know I can put all kinds of suction-cupped sunfolds with nice pictures to the back window, and no, I'm not doing it
So my actual question is/was, can I apply film to the factory-tinted back windows, ie. do they have already films on them from the factory. If that would be the case, another layer of film wouldn't probably stick on very well. But if the glass itself is darker, I can obviously add a film layer to it - I think 50% films on top of the factory tints would be perfect for me.
I understood from some of your replys, that this would be the case, and the back windows could be tinted more by applying films on them, but I'd like to be sure before driving to a local tuning
shop and making fool of myself (it's much nicer to do it on the internet
)