I've just read had a look in the clio handbook, and it says
''Heated rear screen
This function ensures the de-icing and demisting of the rear screen and the heated external rear view mirrors [if the vehicle is fitted with them]''
That doesn't really answer my question, but surely at time of press the MK2 172 [Mines a 52 plate] was the best clio on the market, bar the V6 for gadgets?