In That Was Then, This is Now, why did Connie condemn Mike when he dropped her off at her house? What do you think happend to his brother's car?
As a young black woman, Connie has been persistently victimized by white men and by the racist attitudes of white people as a whole. She finds herself unable to escape this worldview and struggles with understanding how or why a white male would be willing to help her. Although she accepts a ride home from Mike after his gang harasses her at the convenience store, she still does not fully trust him. After all, he is a stranger and a member of the gang who was just giving her trouble.
Thus, she calls for the group waiting for her at the house to attack Mike for two reasons: 1) out of distrust for Mike and white men as a whole, and 2) to maintain the status quo in the tense relationship between white and black folks. This is evident in her language choice, as she very specifically demands that they "kill the white bastard." If Connie had defended Mike, it very likely would have been received as an act of betrayal by her "gang."
Finally, to answer your last question, since Mike is in the hospital following the beating, the car most likely took a bad beating in the attack as well.
VERY good question. In my opinion, and what I teach my kids, Connie condemned Mike after he took her home just out of fear and being sick of being victimized. Although Mike was nice to her and took her home, he did fraternize with the boys who tormented her at the store. Guilt by association. Now she had the opportunity to teach one of the white bigots a lesson by doing the same thing to him as what is done to her on a daily basis. Granted two wrongs don't make a right, but sometimes it just feels good to have a lil revenge.