[MrKepan]

It happened twice already. I reversed out of the parking space, put into 1st gear, give it a little gas and "Bang!", felt like I hit a rock under the car or some hit me from behind. First time it happened as soon as I pulled forward. Second time it happened when I drove 5 yard and the "bang" is not as big as the first one. What could be the problem? I haven't talked to the dealer yet. I would think they will not find any problem since it only happen very occasionally. But it definitely sounds mechanical.

Please, anyone shed some light on this. I really appreciate it.

It drives normal and I haven't noticed anything different yet, hard acceleration is fine, too.

2010 128i, Sport Pkg, Manual