You'll be fine. Tint your windows, tilt the moonroof, crack the windows open a hair, whatever. The effect of black versus temp doesn't really magnify the seat temps. If its hot, its hot.

Our X3 is white with gray, which is pretty ideal in the summer. However, that doesnt mean I won't burn myself any worse than my Lexus, which is white with black leather. Just use the convenience open feature, let some hot air out, and/or put a towel over the seat.

And yes, jeans with light leather is a no-no.