i don't have much experience with clear bras myself but i had a buddy put one on the front bumper, hood (half way), side-view mirrors of his vette and after a few years of natural fade, you could see a noticeable difference between the protected/non-protected paint (his car is black)...will it help protect...yes...but i guess there are always negatives that go with the positives
as far as your car choice...can't go wrong with the z...i love mine