i keep noticing it too!!! im a little bit on edge about the whole temperature thing on mine at the moment anyway!!!!!!!!!!!!!!
i have some bonnet raisers to try to get a bit more heat out, i know people dont like them but they are there for a reason!!!!!!! i thought the same about the heaters too, cold is crap!!!!!! just open all the windows and the sunroof and forget the heater!!!!!!