A teenage girl who survived eight days stranded in her car after it crashed and tumbled into a ravine is alert, sarcastic and entertaining her doctors from her hospital bed, her sister said Wednesday.

Doctors said 17-year-old Laura Hatch (search) may have been saved by her own dehydration, which prevented the expansion of a blood clot in her brain.

"She has a very strong personality," her sister Amy told ABC's "Good Morning America." "I wouldn't say she necessarily knows what she's saying all the time, or what's going on, but she's strong willed and sarcastic and she's definitely giving them a run for their money as far as giving them attitude.

"I think that's probably part of what contributed to her survival is that she does have such a strong will," she said.

Laura Hatch remained in serious condition Wednesday at Harborview Medical Center (search). She was being treated for dehydration, the blood clot in her brain, and broken bones in her face.

The Hatch family had almost given Laura up for dead, and sheriff's deputies had said she was probably a runaway. She was found Sunday, badly hurt and severely dehydrated, but alive and conscious, in the back seat of her crumpled 1996 Toyota Camry.

A volunteer searcher who said she had had several vivid dreams of a wooded area found the wrecked car in the trees.

Laura's twin sister Karen called her sister's survival a miracle.

"We've heard officials, doctors people from the rescue crew saying this is a medical miracle," Karen Hatch told ABC. "I don't know what I believe in, but this is a miracle."

Laura Hatch had last been seen at a party on Oct. 2. The initial search was slowed because there had been underage drinking at the party, and the young people who attended would not say where it had been held, sheriff's officials said.

Amy Hatch thanked the community for the "enormous" support her family was given during the search.

"We have had tens of thousands of people praying, e-mails so much support and I have to feel that we all felt it and that Laura must have felt it too," she said.