Well lets put it this way, there is a blob on ebay and it has a cracked numberplate, and extremely minor damage to the fron bumper............ and its CAT D
the repairs i would imagine would not cost more than £100 with paint and a new plate!
my old green scoob, had NO accident damage whatsoever!, somebody had tipped paint stripper on every panel, so it had a full respray, Also CAT D.
So i dont think it takes a lot for them to CAT D a car!