I was also thinking she probably drove, because her car was probably where she left her coat (she must have had something on over the see-through negligee when she arrived, and it was not in the house nor in Kim's car), but perhaps not. She may have been too drunk to drive. Her boyfriend may have dropped her off, and she was so drunk she left her coat in his car.
Would that arrest record have turned up any recent license suspensions? If she had had her license suspended and wasn't supposed to be driving, and knew she would be deaing with the police, perhaps she dropped the car off for that reason.
She didn't have a license.
Someone posted another article with some more detail on the defense timeline
http://www.freerepublic.com/focus/f-news/1607267/posts?page=874#874
States the last photo was at 12:41.
A photo (must be the last photo at 12:41) shows a lacrosse guy helping Mangum into Kim's car.