One other thing that could possibly cause premature brake wear would be if you live or drive in hilly terrain quite regularly and use the cruise most of the time. The car applies the brakes to maintain your set speed on the downgrades. Incidentally, have you actually pulled the wheels off to inspect the brakes? I was getting a brake warning a while back, and when I pulled off the right rear (it was indicating rear axle brakes) I found the wear sensor just dangling in the breeze. I reattached it, but the warning remained despite having at least 90% of the pucks left. I then ordered up a new pair of sensors (a front and a rear. there's only one on each axle. ($12 on ebay, German made BAP's, too), replaced the rear sensor, and the warning went away. front axle sensor, incidentally, is behind the left front tire, just fyi.