The engine has been this way since new, and the salesman told me that this is normal, but now I am having some doubts. The noise frequency is approximately 1/4 or 1/6 (one-quarter or one sixs) of the engine RPM. It either means that one single cylinder valves are not adjusted properly, or this is the noise of the direct injection pump (that pumps the fuel once per engine cycle, as far as I understand, and this also would be 1/4 of RPM). The noise is coming from the rear passenger cylinder block (where the high-pressure pump is located). So, either the rear side passenger cylinder, or the pump.
The valve adjustment on this engines cost thousands dollars (at least, this is how much the dealer wants). I hope this is not the valves, but I really do not know.