For many months this issue has been getting worse to the point of seriously annoying me and making for a very unpleasant driving experience
any tiny bump at all between 5-40 mph makes an awful rattling noise somewhere from the rear passenger area
big/giant bumps and shaking the car in every possible way while parked makes no noise, high speed, no noise
I changed the wheel, wheel bearing, shock absorber, ripped everything out of the rear of the car including seats and carpeting and rear deck down to metal and no impact
finally I was thinking that it might be the rear suspension bushings so I was all ready to buy the Febest NAB-116, 117, 118 and pay some guy a fortune to replace them
then I decided to go back to a mechanic and get another opinion, so, he can't find it, having looked everywhere just like I did and then decides to punch the right rear wheel
and there it was, a small rattle, so we kept hitting it with some force and listened in to where it was coming from (should have been the first thing before replacing any parts, duh)
long story short it was coming from the brakes, so he says ok lets replace that, caliper bracket and everything (ok, sure buddy, I'll think about that, gave him 20$)
some time later I pull the wheel off and unbolt the caliper and take those caliper guide pins out one at a time, and they looked kind of dry
so I filled that nice with a big load of permatex super premium ultra synthetic brake lube (did service while I was down where) and pit the whole thing back together

long story short, the insane rattle that I wasted a ton of time and money on ended up being fixed by a 3$ bottle of lube, unbelievable.