I found this video of a guy mirroring his Andoird using just Chromecast ($40) and USB-AV converter ($16), into his Lexus IS screen.
But I guess we can't do this because BMW doesn't provide an AV input, our aux input is just audio.
Damn you BMW...
http://youtu.be/vgTaAwB951A
[u2b]http://youtu.be/vgTaAwB951A[/u2b]