Even the computer will be all right for a few hours. I've traveled with mine in the trunk of the car for several hours in cold weather. The MacBook Pro especially gets very cold to the touch on its outside, but it won't really harm it. If you know you're going in for the night, I would take the computer in. The rest of the stuff is fine. I have a Sirius receiver that's nearly always in my car, regardless of where the car is or how long it is parked. We have a basic Garmin as well but haven't taken to having that in the car all the time. There's nowhere to mount all this stuff!