Not really ideal for transporting cars, there's nothing substantial to lash the wheels down to unlike a proper car trailer. They seem to have some light duty lashing rings, but it looks like a decent ratchet strap would pull those out quite easily.
When you get to that weight trailer do you not need to keep an eye on the combined gross weight of vehicle/trailer and a possible requirement for tachograph/driving hours compliance? Recall seeing on one of those motorway police shows that a landrover towing a trailer with another landrover on the back got done for being above the gross weight limits and required a tacho to be fitted.