The car is driven daily, and the driving overall is a combination of city and highway (more city driving but a long ride at least once a week with an italian tuneup thrown in for good measure).

The groaning is NOT like when a wheel bearing is failing - it is much more of a grinding-like noise than a whirring-like noise (which I associate with failing wheel bearings).

Bribenz, you may have hit on the source of the problem - but why does the noise go away once the car is well warmed up? And why would it take half the pad life for this condition to show up - wouldn't it have showed up much earlier?

Robert