If this isn't related to tire balance, then I wonder what it is?
Since this has never happened before in a BMW 3 series, as their steering has been nearly perfect, then the electric assist becomes suspect.
However, the electric assist is not "active steering", meaning it can't actually move the steering arm to say compensate for cross winds, or help correct with DSC.
Maybe the actual steering rack mounts weren't torqued properly?
Or, the mount bushings are faulty?
Could also be some defect causing more play in the steering pinion gear.
This would directly result in the steering wheel moving left to right.
But then, I would think that at different speeds any play would result in different rates/frequency of oscillation.
Do you guys with the problem notice the vibration change in intensity at speed?
Another thing could be electric assist or EPS. Since the system has the ability to add and reduce steering effort via servotronic, maybe it's not holding the effort steady.
Rather, it might be holding and letting go, allowing the natural wheel motions to come through with no damping to control those motions.
In my 06 A4, I could easily remove the servotronic fuse and render it dead.
Is the servotronic fuse accessible in the F30 to remove it and see it it makes a difference?
In the A4 once I removed it low speed effort was very heavy, and once up to speed I couldn't notice it at all. When it was fully working slow speeds gave a light effort and then got heavier as the cars speed got above 15-20mph.
I'm only offering that as a suggestion. If you try it, it's your own decision.
It's just one thing that could be checked by a BMW tech, and eliminate if nothing changes.
In my A4 all it affected was low speed steering effort.
What's additionally puzzling is that this vibration seems to come at around the same speeds as wheel balance, typically above 50mph.
But, with unbalanced tires the vibration typically gets stronger the faster the vehicle speed. And then some times the vibration actually goes away once the car is above say 70mph.
Does this happens to those of you with this vibration problem?
Do the vibes start at a certain speed every time?
Does the vibration intensity change as you go faster?
Does it go away after a certain MPH?
I too would be pissed if my new car had steering vibration.
It doesn't matter if the car costs $10 or $50K, steering vibration is not acceptable. It's quite annoying, and it completely removes any steering feel whatsoever.
Since the steering wheel is the most direct connection between driver and automobile, any vibration or problem becomes unacceptable as it's constantly felt, and makes driving the car an annoyance rather than pleasure.
I really do hope my 3 doesn't have this issue as I would be as pissed as you guys. Before signing the papers I'm going to insist on driving the car before I finalize the deal. Since there isn't a cure yet, I don't want to take delivery of a new car hoping and waiting on BMW to find a cause and fix.