Unfortunately this seems to be quite common.
See https://z4-forum.com/forum/viewtopic.php?f=3&t=100725&start=180
I would also say worn bushes and the runflats are the first things to check.
Also make sure the tyre pressures are correct. Mine were over inflated and dropping the pressures to the correct psi helped massively (but hasn't completely cured it)
I also have a broken rear spring which might not be helping.
When you have sorted everything that needs replacing, get a 4 wheel alignment
See https://z4-forum.com/forum/viewtopic.php?f=3&t=100725&start=180
I would also say worn bushes and the runflats are the first things to check.
Also make sure the tyre pressures are correct. Mine were over inflated and dropping the pressures to the correct psi helped massively (but hasn't completely cured it)
I also have a broken rear spring which might not be helping.
When you have sorted everything that needs replacing, get a 4 wheel alignment