Friend of mine was driving an old Ford Galaxy down the road one day in upstate NY and it broke right in two as a result of being so rusty.
He also had a similar car that had been in a bad rear end collison. He simply moved the fuel tank inboard, cut off everything from the back window aft, attached a piece of plywood right below the back window and drove it for years. I bet they wouldn't allow that in the UK.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13