I am planning to semi-permanently mount an older but functioning Garmin nuvi 775 gps on the dashboard vent of my 1999 XK8 coupe. I have a clip that will allow it to be mounted in a good location but I need a power source for this device. What is the best and closest 12 volt source I can use to power this? Ideally, I would like the source to be switched.
Any recos?

 

fuseboxes to left or right with a choice of permanent live or ignition switched