The Munich registered Triumph Spitfire looks like it's been parked next to the sea...and that's a measure of how convincing your rust effects are! Really convincing...so much so that I'm wanting to coat them in Kurust!
Before scrap cars were required for export to China, dumping them became
a common problem in towns,and also in the countryside. Here in the Highlands, people would sometimes drive them onto a secluded beach where the tide and salt spray would dissolve them after a few months. Your impressive car-rot
effects recall some of the hulks I've seen on beaches.
As has been observed elsewhere,sometimes with lively debate.. and in other threads, tanks in service..and even those recovered by maintenance units from battlefields ( Kursk, for example) are not allowed to get rusty. Abandoned and destroyed (largely unrepairable) tanks go rusty....and, in the process, reusable components are often scavenged from them..
Rusting hulks would look great on a model battlefield, though, and I've seen people use 'destroyed' tanks in Youtube vids of battlefields to give the feel of authenticity
"Get your facts first, and then you can distort them as much as you please"- Mark Twain.
It reminds me of my old Dolomite Sprint! 
