it does get hot in the cabin with black leather, black dash and black carpets. I usually try to leave the sunroof open to tilt when parking it (as long as it is secure). The a/c can be a bit weak to blow the hot out, but it isn't as bad as that in my olf 205 GTi.
I find the heated seats on three just lovely and keeps me nice and warm.
If any one of my front seat passengers start to give me the shits on a hot day I might just turn it on FULL