I drove a Seat (you don't have it in US) in Spain which had all windows tinted. However, the difference was that all of them were done with LLumar clear nanoceramic film. It was not noticeable at all - looks just like factory glass. But as it was nanoceramic, it did a really good job in heat rejection. Later I compared that film's specs to other dark(er) films. In order to achieve that levels of heat rejection LLumar ofered you had to go as low as 30% or even lower (the LLumar was 80!).
What about cops? Inspection? Doesn't that tint bother all of them?