Interesting
I was recently in Australia, and took my TomTom satnav with me (having bought an Oz map!) to use in a hire car. Its power lead has a USB plug on the end and the usual way of powering it is to use a 12v to USB adapter which plugs into the cigar lighter socket. However, for some reason, the cigar socket on this particular hire car didn't work - but there *was* a USB socket - provided to allow MP3 players etc. to be connected to the audio system.
When I plugged the TomTom into that, it displayed a message suggesting that it thought it was connected to a computer - but it was possible to cancel that and just use USB to power it, and that worked ok.