I'd take out my gpu as a best practice i mean its not like its hard or time consuming to take out and replace... whether it's necessary or not is debatable. For just driving I wouldn't worry about it that much.
Ok thanks guys, I think I feel confident enough now to just leave it in there. I mean i will be putting the whole Coolmaster case back in its original box with the styrofoam braces / brackets supports things and ill be transporting it on it side.
Im probz gonna put a duvet round the whole box as well.
And when you think about it, when people buy pre build systems online, the whole machine comes in a box, preassembled I guess.
I've driven across country multiple times with multiple systems, never had anything break. I always laid it so the motherboard side was down on the back seat of my car, like how a test bench is set up, and moved the front seats back to make it snug so it wouldn't move. And in my time working at a pc shop I have only seen a few times where the pcie slot got ripped off the motherboard in shipping, and I'm sure you will be more careful than ups or fedex.
I travel back and forth with my PC from uni to home (100 miles), all components still inside, and haven't had any problems. I transport it in the motherboard box with the shipping foam, motherboard side down. You should be fine.
I might be able to offer some insight. About a year ago I moved from Alaska to Connecticut (for a three year assignment only, this state sucks balls). I have a CM Stryker case. I built a custom box out of 2x4s and .5" plywood then lined the inside with 2" thermal foam. Leaving all the of guts inside, I emptied the coolant and stuffed the case full of packing peanuts. It had no issues when it arrived 45 days later