Firstly, considering the distance you have to travel, make sure you can inspect the car in the daylight. Under lights, little things can be hidden.
Check for problems with the paint, like being uneven or even missing in places. Check ALL the fluids, tyre pressure, including the spare, under the seats for loose connections etc. Also check to make sure the roadside assistance details are there. Take it for a drive around the block and check for any noises etc before you sign.
Also, any factory fitted options need to be checked that they actually work. Trust me, I have been thru this with another car.
You will look a bit of a goose, but better that than having a problem 500kms down the road.

