My '08 X makes what I can only best describe as being a soft conga
drum sound and is most prominent when I drive off slowly with it after
the car's been sitting around for a few hours, especially in its first
drive in the morning.

But sometimes I can still hear this sound when the car's relatively
warm as well. For eg., if I dropped into a supermarket to pick up a
few things on my way home from work, and I drive off again while
getting out of the parking lot. The sound is not loud by any means,
but it's still audible and the warmer the car, the fainter it gets.

Please have a listen to the file located here,
http://members.shaw.ca/riprock/conga/ There, you'll find a file named,
VORC001.wav. Between the 14th and the 15th second mark is where you'll
hear the sound I'm trying to describe. You might have to turn up the
volume to hear it properly. You hear a faint click immediately
followed by the conga drum sound for a second.

I can reproduce this sound when I've gently eased into my third gear
and the car's at between 1700RPM and 1900RPM, probably going a little
over 20 mph. But sometimes I'll hear this sound for a second when I
start my X after having parked it overnight as well. As you can hear,
the sound is not continuous. It's just in the 3rd gear, easing into
that RPM range and speed.

Once I'm on a main road though, I'm accelerating at a faster rate, so
I don't or can't hear the sound at all. I wanted to try to go as slow
as I've decribed in the above paragraph while driving on a main road,
but the cars behind me probably will honk, so I haven't tried.

I haven't taken my X to the dealer yet because it doesn't seem to be
causing any problems and also, partly because the best chance I have
someone else will hear this sound is when the car's been left there
overnight and I go back there in the morning and drive it myself to
reproduce the sound properly, which poses a great inconvinience to me.

Are any of you familiar with this sound at all? Can someone guess as
to what might be causing this sound? Do you think I should take my X
into the dealer right away to have it looked at? Any suggestions or
advice would be greatly appreciated. Thanks in advance for your time
and courtesy.

Oh, my X has 2100 miles on it right now, but I've noticed this sound
pretty much almost from the beginning of my ownership. And I use
premium fuel with 91 octane rating all the time.

Thanks for your time and courtesy.