I have seen damage to cars on the top rack of car carriers, located up front. the exhaust stacks, apart from being dirty and coating the top cars with baked on grime, spew out 900 degrees.
My son't first Rover, a LWB Rangie, came up from Miami on the top of a car carrier, who was making a drop-off on a quaint, tree lined reidential road in NJ. Result was nice crease in the roof skin. The trucking compny never made good, and after I had called about 6 times, the owner started swearing at me, and I don't mean saturday afternoon on the golf coarse type swearing. I got my pound of flesh out of him, thanks to some very good Cuban friends.