Just put int on the rear deck lid. That's where I put mine on my last 323 and it didn't scratch the paint in over a year and a half on there. Sure if you constantly move it around it could scratch but it would never scratch through the clear coat. So even if it does scratch a bit when you take it off to sell the car, it will come out with a simple buff and polish. The reception is sure to be better if it's outside vs. inside the window.