Recently installed this (see photo) USB Charger Socket between the upper windshield and dome light. The socket is wired into the dome light so that it is always hot. Really easy install and great location for powering your dash camera and GPS unit. Also works well for charging phones, but I plan to soon add another one to dash for that purpose. You can order the socket from Amazon, it's called: "
Highest Power Dual True 4.2 Amp USB Charger Socket," cost is about $13.00 plus shipping.