I did this with my Garmin V. Super easy. Just cut off the car power plug, and solder the wires onto the back of your cigarette lighter socket (if you've got one). Works like a charm If you don't want to cut the cable... you could just buy one of those cheap socket splitters at Radio Shack, plug the Garmin into that and tape it in good, then cut the wires of the splitter so you have just one socket and solder that on.