The woman, in her 40s, was pale and cold and started shaking as carpenters from Max Mackenzie Builders stopped on the North Island's State Highway 41 and ran to her aid, covering her in their jackets to warm her up.
The group of Taumarunui builders were on their way to a building site in Omori near Taupo around 8am yesterday when they spotted the Toyota Vivi from SH41.
Site foreman Ricky Balloch said they pulled over to see what had happened, and expected to find a dead person.
As they wrestled through the toi tois to get to the car, which had rolled twice over a ditch, they yelled out to see if anyone was there.
The car had landed on the driver's side and the front window was hanging off.
"We got close to the car and said, 'Hello, is anyone there?' and we heard this real faint 'Help me'."
When they saw the woman, she still had her seatbelt on but her left arm was broken so she was unable to use it to free herself.
"She was freezing, we got our jackets out of the van and piled as much on as we could. And just kept her calm really and called for help."
He said given how cold she was, she was extremely coherent and able to communicate very well.
Balloch said they called 111 and ran to the car to find whatever they could to warm her up.
Temperatures fell to about -4C on Sunday night as the woman sat and counted 26 cars drive past her in the dark.
"She was so grateful. She was unbelievably grateful. She couldn't thank us enough.
"She said, 'I thought no one would ever stop' - because she had been there since 9pm at night."
The woman had been to Hamilton that day to collect furniture, dropping a friend off in Taupo before heading home to Taumarunui.
She told the men as they waited for help that her car had slipped on the ice.
St John paramedics, firefighters and the Greenlea Rescue Helicopter arrived at the scene and the woman was flown to Waikato Hospital.
A rescue helicopter spokesman who attended the crash said the woman was "bloody cold" when they arrived. They used a thermal electric blanket to warm her up.
A DHB spokeswoman said the woman was in a serious but stable condition last night.
