Nice anecdote, wolfetone. Some of us like proper science and engineering though, so here's some actual data on 5 mph collisions:-
Scroll down until you find the Volvo S80 thing. A 5mph crash head-on into a brick wall would cost you $5,137, the most expensively damaged car in the tests. So, I know the data's from 2000, and it's a specific model, but I'd suggest some actual research rather than rely on a friend of a friend, before deciding which car to buy!
Now, bearing that data in mind, a more expensive crash isn't necessarily a bad thing. You didn't mention what happened to the occupants of the cars. I think I'd prefer to be in the Matiz you mentioned if its airbags and crumple zones cushioned my impact, whereas the Volvo driver got their face smashed against the windscreen, and their sternum broken by the seat belt. I think that explains the expensive repair job for the Volvo in the 5mph test.
p.s. My (worthless) anecdote. I personally have seen a couple of accidents on the motorway, where cars bash into each other nose to tail. You end up with a line of cars on the hard shoulder with damage to front and rear where they've been sandwiched. Both times there was an apparently undamaged BMW 5 series in the middle of the line.