[Giller]

Yesterday, driving home when I slowed and stopped, as the car in front of me was turning left. As I sat there, I heard a very obvious Bang. It sounded like someone had just hit me. But I was stopped, open road, no birds or animals in sight....but really sounded like something ran into the side of my car. Sounded like it would have hit somewhere around middle-back on passenger side. But there is zero evidence of anything hitting the car. And I drove away just fine. Fluke, or could the noise have been mechanical? Thoughts?