"One particularly annoying one occurs in cold weather when I'm turning right."
My 850 does the samething, it's the heater blower in my case. When the warm weather arrives, the noise stops and I forget about it until the next winter (I really should do something about I suppose). Check your glove compartment too (door and contents), the GC door used to make some rattles.

Paul
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'98 V70, '95 850 GLE 10V