It depends on how you personally are in dry heat (rather than high humidity etc). Morocco inland in the summer can be extremely hot, as has already been said. Last time I went I had three friends in the car - two of us were fine and didnt mind the high temps, and two found it uncomfortable.
As has been said, DRINK water copiously (alcohol, coffee and fruit juice speed up dehydration) - and, well, this has been the subject of debate on here before, but my advice is not to use vehicle airconditioning when offroad for protracted periods as it saps engine power and dehydrates cabin air. Not all agree, but then I guess not everyone's had to tow folk out of the desert in advanced stages of dehydration due to their aircon....
'91 LR 110 Def/Disco hybrid "Elsa"
Bring me the horizon....