I was parked in my parking space I reversed into the space. I left the car running in park to dispose of trash. When I come back to my car to retrieve my cell phone and key out of the ignition. When the car turned off, the car began to roll down as my space is at a slight decline and the result of this was me bumping into a motorcycle who is parked directly across from my spot. I attempted to brake and I wasnât able to steer as I had vehicles to my left and right and this happened in a distance of maybe 20-25 ft. The other party was notified no one was hurt but both my vehicle and his bike took damage. I have damage to my front grill because of this malfunction. This has never happened before but as this is a new car, this concerns me greatly and has been brought to Toyotaâs attention. I wanted to file a complaint as I know others have my same vehicle and they may have had or might end up in the same situation as I was in. I believe it is the parking brake that was the issue.