Bummer for sure...the culprit may have not known he hit you. I backed up one day into UPS truck...I just didn't turn tight enough on my backup, looked thru my mirror and saw I was to close, hit my brakes hard and never felt the impact do to a sudden of stopping. UPS truck bumper, not even a scratch...my Nissan bumper cover showed a nice little scrape. I would always assume a Porsche owner would bone up to a stupid mistake...I would even shiver thinking that jerks like this would be a Porsche owner.
Yes, I told the UPS driver I tapped his front bumper. We agreed no damage, but he had to report it.