Hi
I purchased a second-hand 370z a few months ago. Only 1 owner, really low milage (~13k), no mods (that I know of - but who knows if it was reverted back to stock before it was sold by the previous owner). Complete service book. Recently serviced.
I haven't used it much (probably less than 1k miles), and I always let the oil get up to operating temp before I put any significant load on it.
I didn't have any issues with the car to begin with. Then, after a couple of weeks, I started to get some loud clatter when taking off in 1st gear. Nothing whilst driving. Then all of a sudden, the horrible clattering noise started the other while I was driving on the highway.
So initially I though it was a transmission/clutch-related issue, but now I'm more inclined to think it could be engine-related.
Have a listen in this video clip...
Whilst driving on the road (I did a very short test drive before shooting the above video), the noise is not always present. Or maybe it's just not always loud enough to be heard. I'm unsure.