Hey Kuan, sorry about your bike rack.
If it makes you feel any better, I just got rear-ended tonight in my E-320.

Guy hit me from behind in rush hour traffic. We were only doing about 5 mph, but it was enough to crack the rear bumper on my car.
He offered to give me $150 on the spot to take care of it. I told him it'll be a bit more than that! Got his info, and I'll get an estimate on Monday if possible.
I hope I'm not a sucker: I don't feel a need to call the cops on people unless really necessary. The guy seemed honest and gave me his lisense info including a cell phone number. I called him right there and saw that his phone did ring, so I hope the rest is truthful.
He said he didn't have his insurance card with him, but gave me the name of the carrier- US Auto Insurance with a policy number. I think it's bogus, because a google search yeilds no company by that name-- unless they're out of Texas.
We'll see.........