Bee,
This is without any doubt the warmest car i have ever owned, even on a "normal" day the cabin is warm. Like you say it can't be good for all the leather. I've even noticed that when i first turn on the blowers they always produce warm air, then after about 5 mins the air reduces to luke warm, but never cool air, unless the AC is on.
I'm sure this is a fault ? Warm air blowing through the vents even when the dial is on low !
Yet some members say no and this is normal. Well it's the first car i've had that does it.
Getting back to the leather, you must make sure that you "feed" it to keep it soft, even more so when you cabin is like a furnace.
I use Megiures leather cleaner and preserver once a month, wipe on and buff of, easy.
It will help stop "shine" and stops cracks developing by re-nourishing the leather . :thumbup: