Vibration from the rear of the vehicle

look at this link..
5 Causes of Engine Vibration ...
If your car is shaking while it's on but not actually moving, then it's likely not the tires. This usually means there is something broken in the engine, such as the radiator fan or engine mounts. Fuel system issues can also cause the car to shake even while standing still.

Why Is My Car Shaking and What to Do About It? - EnkiVillage

I believe you gain access to it by removing the rear seat then a cover plate in the flooring. Hope this helps.

The vibration is caused by worn driveshaft parts. The BMW driveshaft is flexible and has a rubber universal joint called a Guibo and a center support bearing that must be replaced when worn or old. The parts are about $100 (60 for the universal joint and about 35 for the support if you buy them from autopartswarehouse.com )and the labor is about $250 at a good independent repair shop.

possibly bearings in your wheel hub. they get quiet noisy when they need changing

axel barrings are bad had that problem before

try and rotate the tires if on has a problem the vibration will change to the rear

i would suspect somewhere in your front end you have a compliance bushing with excessive movement. these cars front ends depend heavily on these style bushings, and as they wear you can start to see tire wear patterns, looseness in steering, and high speed vibration. make sure you have the front end inspected by a shop that is familier with these types of cars. good luck!

wheel bearing

Sounds like you may have a worn out CV joint and the clicking may stop with an oil change. Good Luck

Same thing with one of the customers.. It's normal nowadays with auto trans vehicles, since the got ect-i's.