I pu this on Gen. Tech. Help as it's quite common on other Jags., indeed other cars.
THE NOISE: A kind of buzzy-rattle from what sounds like the area around the radio-heater console somewhere, even the glove comp. (Mine is UK so that's to the left).
WHEN: Not when it's cold, but when it's esp. part warm. Affected by certain roads and tyre roar from same.
THE AREA: Turned out to be something to do with the winscreen/shield where it abutts the scuttle area to left of car. Found by stuffing an old towel into crevices various around there, including the demister vent.
THE FIX: I got a new piece of pipe lagging, the kind for lagging 15mmm. pipe as in plumbing. There's two kinds, a soft squidgy plastic foam, and a rather harder kind in pale grey with a smoother surface which can be stuffed into the gap between windscreen and scuttle quite decoratively (I thought). I did the whole width left to right.
A longish journey this morning, all sorts of roads -- no buzzes!
However, having done this kind of thing before, I'm keeping fingers crossed...
Leedsman.

 

Do you have an X300 by chance?

I'm sensitive to funny noises and my '95 is making me nuts with a noise just as you've described. I've spent hours trying to track it down.

Thanks for the head's up !

Cheers
DD


PS- if any X300 owners want to see a list of rattle fixes, just shout. I've traced and repaired many on my car.