Sylon, you are extremely lucky! The only thing I can think of is the evap system that's attached to the battery holder on the underside of your car. I have heard some horror stories on that needing replacement.
Glad no one was hurt. I have learned that these cars are rather interestingly built. When I was rear-ended I thought the bumper took all the force of the impact. When I took it to BMW collision for inspection, they found that there was a bit of damage to the quarter panel too. (This was cause the driver hit me from the corner and not straight on from the rear.) I wouldn't be surprised if your fuel evap system has been affected by the incident.
Hope it all works out!