We have.. in fact... discovered a car that suits most of the requirements, and that is the Citroen Berlingo Open-air. Not a very "cool" car

I think you are spot on with the Berlingo, or its Renault or Fiat equivalent. In fact, the Daily Telegraph here, had an article saying that it was the new cool.
I had one in Majorca last year and, apart from being everything you want for children, dogs and paraphanalia (you can sling everything in, without too much careful packing), it's ace for a 6' 3" driver.
I think it's much more the new 2CV than the Pluriel, which is, however, a very clever car.