If anyone's interested, I have a whole bunch of suction-cup camera mounts on the way from the states at the moment.
They have a standard-thread mounting screw on them, so if you already have a cheap DV camera you can use these mounts to attach it to the windscreen/outside of your car. Bit easier than rigging up a tripod on the back seat with bungee cords!
pm me if interested, I expect them to arrive mid to late next week and can supply pics and better info then.