Not sure the best way to describe the noise, sounds mechanical... like a very fast paced actuator fluttering (turbo wastegate or something with variable valve timing). <p>Happens as the RPM's are ramping down during upshifts. Most noticeable with moderate acceleration and the tranny shifting from 1 to 2. Notice it most when cold, but still think it's there after warming up. <p>Half tempted to go "test drive" another XC60 to see if they all make the noise, or if I may have a problem?<p>By the way, the vehicle is < 2 week old. Just hit 500 miles and I just love it. Only disappointing thing with the car is that I didn't know about the tan colored pillars and headliner when I ordered the off-black interior. Wish it was black to match the dash/seats - and not to show dirt from fingerprints, home depot runs, little kids in the back seat, etc. Probably wouldn't have changed my purchase decision, but I'm a perfectionist so I need to complain about something!