Thank you all for responding.
First of all, can you guys see something odd on the green car? Please look at the rear and front pictures of the car. Look at the top of each bumper, between the body.. Is the car missing something? May be I was wrong. But try to compare rear and front pictures of the green car car with the black car or any other 500E. Do you see what is missing with the green car? Has it ever been in accident?
Second, I went to see the car. According to the seller, it has been one owner car and has been serviced by MB since new. There was nothing much to tell because I did not test drive the car. I wanted to do so but there is not much gas left. I even did not notice about what's missing between the body and the bumper untiil I got home and compare the picture with other 500E. All I know is there is no any strange noise with the engine but it does not mean much. Not until you test drive the car.
David Hendy, It's very nice to know that you live in brooklyn. Who else lives in NYC? I live in queens. May be we can test drive the green car together.