Why not just mount it in your vehicle and call it good? After a few times of taking it in and out you'll decide it's probably easier to just leave it out and you wont ever use it. However, it would be very nice to have two antennas, one for the house, and one mounted on the vehicle so you can bring the radio in and use it inside. You'd need a AC power adaptor but that could be rigged up or bought easily enough. I've seen people mount the radio in a tool box and mount the faceplate and the power wires on the outside. Just need to watch the circulation and make sure it doesn't overheat or anything. You could hardwire the power wires to your battiery and run them into your vehicle terminated with some kind of quick disconnect plug . To answer your question, no, it doesn't need to be grounded. I do not recommend plugging the radio in to your 12v outlets. It's very likely you'll get a lot of 'noise' through the vehicles electical system. You'd be much better off hardwiring it directly to your battery as previously mentioned. Running the antenna would also be a pain, so I would suggest leaving it on the vehicle.