Radar detectors are now legal in the UK but totally illegal in France - I believe they still use the Guillotine for offenders! I have a Passport Solo (I think that's it name) which is battery powered and means I don't have any wires dangling.

Many, many years ago, I drove an old (ish) Mercedes that belonged to a friend and that featured (on the cassette deck in the dashboard) a mini-jack socket (a walkman like headphone socket) which allowed you to plug any audio product straight in - such as mini disc, MP3 etc. I think that would be such a useful addition.

The Murcielago has a single CD player (as well as a CD changer) which is a useful feature as I cannot be bothered to change the cassette stack on any of my cars and quite like chucking a single CD in....

Sat Nav is very odd in Europe. If I follow mine I quite often find that a 2 mile journey within London will route me via Scotland and Wales!