I'm having the same issue with my 2013 that I took delivery of in late August. When the dealer had my car last week, I called to tell them that the loaner they gave me was doing the same thing but worse. The loaner had about 6,900 miles on it and the steering wheel shook at the mentioned speeds worse than mine. So I'm wondering if this problem will worsen in time? The dealer balanced the tires - got my car back and it doesn't shake as bad. I've ended up talking to the Service Manager because the Service person was treating me like I was nuts. They just called me back and the BMW Field Engineer asked them to open a info case on my vehicle and to do a hard balance? They admitted to me that BMW is aware of the issue and is working on a fix.
My concern is - will they be able to fix this? Will this affect the value of my vehicle? Will it ruin my tires early?
I'll give them a little time to figure this out but I didn't order and wait two months for a $49k BMW to have this type of issue.
Word of advice - test drive the vehicle between 40 - 60 mph. Put it on cruise control and see if the steering wheel starts shaking before you buy it.