on the ferry.. all ferries are both for cars (buses too) and people... went there almost exactly 1 year ago so don't remember exact details but surely easy to find out...
I am a Chongmingnese and I sincerely hope I can help you with anything.
It is quite easy for you to reach Chongming in your own car.You can drive to either of the three port to Chongming and then take a boat there with your car. Three ports are as follows: SHIDONGKOU, BAOYANG AND WUSONG.