Unfortunately brake life is dependent on many factors, including how and where you drive. Softer brake material, used in high performace pads, does wear out quicker. If you put in a harder pad, the trade-off for extra pad life is that you will wear out your rotor quicker and have less stopping performace - not a good solution.
I had a Mercedes in the 80's and it needed front pads every 3K miles (at every oil change) and I was told by every Mercedes Dealer and independent mechanics that it was normal! I never bought another Mercedes again after that!
I have had two BMW's and they seem to go 25K-30K miles on brakes. However, BMW dealers insist on changing the pads & rotors together - so it is still expensive.
I agree that it is disappointing if we are going to have to put brakes on our G35's at 15K miles less though.

 

Guys, I have a Volve 850 and was extremely unhappy with the Dealer's mechanic' workmanship and the quality of those 'GenuineVolvo parts-brake pads and rotors' and thinking of getting rid of it and the G35 seems like a very good car. I put $2K last year on new front calipers/pads and rotors, and new rear pads/rotors. Now,after 20K mile, the front brake starts to vibrate at slow braking and the read brake squeaked so loud. Complain is useless as its wear and tear. But now that I hvae seem this discussion, I am just wondering if G35 is a good choice ?

Frankie