A teenager left trapped underneath her car for seven hours after crashing down a mountainside was rescued after her mother used the Find My Friends app to find her.

Catrina Cramer Alexander said she used the feature on her mobile phone when her 17-year-old daughter, Macy Smith, uncharacteristically missed a curfew and didn’t respond to texts or calls.

"The lack of response was out of character for her," Ms Alexander told North Carolina’s TV channel WFMY.

When she looked on the app it showed her daughter had been in the same location for “far too long”, she said.

"I can't explain watching the GPS on my phone with my dot for my phone getting close to hers and then suddenly seeing the tire tracks," Ms Alexander said.

She found Macy pinned underneath her car down a 25-foot embankment in Pilot Mountain.

“I will never forget the sound of my family calling out my name when they found me,” Macy said in a Facebook post. “I hydroplaned at 4.00pm and ran in between two trees down an embankment, flipped my car three times, and landed in my back seat with my arm pinned in between the car and the ground.

“I searched for my phone to call for help but the only thing in sight was my bible. I held on to my bible and prayed harder than I had ever prayed before.”

Paramedics arrived to rush Macy to hospital. The 17-year-old said she fractured her neck and suffered severe nerve damage in her left arm.

“We are celebrating every minute and every milestone,” Macy said.