Being a newbie on here, I have enjoyed reading the Forum pages. So much useful information. I realise that this is a fairly old thread, but I just want to leave a comment in case it is of use to anyone. I had problems with the TomTom falling off the glass, and spurred on by comments that the mark on the glass could invite unwelcome attention, I turned to the idea of using Velcro Squares. A block of 6 on the dash, and onto the back of the TomTom seemed to hold the unit in place firmly and was not shaken loose. I did wonder if the heat from the sun

through the windscreen may effect adhesion, but never had any problems......or hot sun

When not in use, the Velcro on the dash could be used for something else not important, to cover it.
Keep smiling, Ian T