My Pruis is now just about a month old, 2005. With the colder weather (under 45) there are times in my commute to work that I notice a rattle in my left ear. With my kid away in college I know it can't be him. The noise is right at ear level. But I can't determine whether it is the seat belt system or the top of the driver side door actually vibrating. Has anyone else had this problem? I have even opened and closed the door - first time while cruising about 40mph - the car did not like that!!
Check the rear seat directly behind the drivers seat to see if it is properly latched. I had a similar rattle and finally found that the passenger seat was not securely latched. Also check the storage compartment at the bottom of the door. I dropped a coin in it and had a strange noise till I removed it. For some reason noise seems to echo in a Prius and not really be coming from the actual source.
I have the same rattle. Mine is the plastic cover where the seatbelt enters next to the door. When I push on mine it stops. I have been developing a few rattles here and there. Have had my car for a year now.
I too vote for the grab handle (the one over the door). Just wiggle it and it will stop for a while. I often have a problem with the flip-up cup holder rattling. Opening it up usually takes care of it when it happens.
Another source of projected or deflected rattling noise is the sliding cover of the vanity mirror, if it is not closed by firmly sliding it over the detent.
Thanks for all of these options to try. At least I can rull out one right away, the pocket in the door has been empty now for several weeks. I'll start playing with the handle and seatbelt cover tomorrow.