Why wouldn't she be texting about the party from in his car? Maybe she told him she was going to a party but couldn't find the address. Maybe he offered to help, or said he was going to the same party? She was visibly intoxicated, so she probably was not thinking straight. Maybe they went into Tempo to buy a bottle of wine for the party, each had a small glass, they put the top back on, and got in the car to go to the party.
" After 1:08 a.m. Graham and a man with dreadlocks enter Tempo Restaurant & Bar on Fifth Street Southeast. He buys alcohol, they stay 15 minutes and leave together.
1:20 a.m. Graham texts friends, "I'm coming to a party...but I'm lost." It was the last time she had contact with anyone. If her phone pinpointed her location, police have not released the information, and police did not clarify whether the text was sent before or after leaving the bar."
http://www.usatoday.com/story/news/nation/2014/09/19/missing-virginia-student/15890571/