A warning to all SAT NAV users.
My car was recently broken into with nothing of value taken. When the window repair man arrived he told me why. The circular marks on the windscreen showed that I use a SAT NAV, and that is what the thief was looking for. The seat had been moved back in his efforts to search for it. I would never have dreamed that just marks on the screen would cause all this trouble.
In conclusion always wipe those marks away when removing your SAT NAV and never leave the bracket attached when leaving your car.