Help finding middle aged douche bag drivining silver BMW Z4

I know you guys deal primarily with the downtown Austin area, but yesterday I was
out in Cedar Park riding Lime Creek Rd. with my brother in law (Cary
Andrews), and a jackass older guy (upper 50s) with silver hair driving a
newer model (2010-2011) silver BMW Z4 pushed too far in a corner, came
across on coming traffic, and almost ran smack over my brother in law,
causing him to bail into the ditch sending him over the handle bars and to
the emergency room. The dude sped off around a corner before we could get
the license plate, but I did get a good look at what he looked like.

I know it's a long shot, cuz the above description pretty much describes
half of Austin, but If you can ask to have people on the lookout for the
above dude/car combo and send me an email (dj.howl@gmail.com) with the license plate number I'd
really appreciate it.

It's tire slashing time!