Infiniti 2006 G35, rattle in door

I have a rapid vibration rattle in the drives side door that comes and goes. The dealer’s service people hear it on road tests, but can’t fix. Any advice?

Did they tell you what they think it is? Why can’t they fix it? Is it because they don’t know what it is, or can’t they reach it? Last question: is this car still in warranty, and is this a warrantable problem (read your warranty)?

a 2006 car should have a warranty. but, either way, you should have them take off the inner door panel, and look in there.

did the car have a new glass window installed by any chance over the last two years?

have you looked down into the window (with the glass rolled down) with a flashlight, and looked for pen, pencil or other stuff down there?

The problem could be related to the inside latch rod. These are often wrapped in a few spots with foam to prevent rattles.
Sometimes the foam moves around a bit and a rattle will develop. The inside door panel will need to come off.

What are the details behind the inability to repair this? Is this a matter of telling you that warranty will not cover it and you may have to foot the bill?
Warranty will cover a defect if something is broken or due to workmanship. Warranty will not cover something that may be caused by rough roads shaking something loose, things going out of adjustment, etc.