According to rustbucket, Austin news 8 is reporting he hit a Lexus. Pilot could be a tax dodging, class warfare hippie.
One of the other local channels, KEYE, just showed a picture of the Lexus in question. They said that at the same time that the plane hit the building some debris from the crash hit the car. The car was apparently on the road that runs by that side of the building. The windshield of the car showed damage. Channel 8 had said that the car was hit by a wing.