I just got an 09 Z about 2 weeks ago with 37000 mi. I didn't notice any unusual sounds during test drive and was so excited. I babied it while I was getting use to it.
Over the course of a few days I heard slight ping/knock sound from motor once it got to about 2500 rpm. I checked oil and everything was good so decided to take in asap.
Took it to dealer on Wed night and they said will take a look and gave me a rental. Today I found out it will probably need a new motor because they think the rod is knocking so will have to flip the bill to Nissan for new motor.
Guess I should be happy I'm getting a newer motor at no expense to me but at the same time disappointed can't enjoy my new car.
I did some searching on the site but only came across a post or two with someone that had this issue.
I saw a TSB about unusual engine sounds the dealer will check oil and if still noise car needs new short block.