The vehicle was sinking bonnet-first as she unfastened her seat belt and got the cat out of his cage.
''I couldn't believe how fast it went down,'' she said.
''The water was coming in and I knew I had to get out of there. I didn't know how deep the water was and I certainly didn't think it was that deep.''
As the car became submerged, she clambered into the back and ''kicked the hell out of'' a window.
''The adrenaline rush made me put everything I could into it.''
When the window eventually gave way, she thrust the cat out into the water.
Unable to breathe as the water rushed in, Ms Kay said, at that moment, she thought she was going to die.
Weighed down by the heavy woollen coat she was wearing and being sucked under by the car, she struggled to the surface where she saw Wibby heading towards the bank.
''It's amazing; I didn't think cats could swim,'' she said.
Disoriented and in shock, she followed her cat and scrambled up the steep bank, struggling to grip the frozen grass.
Catching her breath, she lay on the frozen ground for about 10 minutes before finding her way to the road to get help.
Soaking wet and covered in grass, she began jumping up and down, and watched in disbelief as six cars drove past.
The driver of the seventh vehicle took her to a neighbour's house, where she rang police. She was soon taken to Oamaru Hospital for observation.
The cat was found at the crash site by neighbours that night.
Yesterday, Ms Kay was still struggling to believe she had survived. She had bruises and cuts and was having difficulty breathing, but said she felt ''extremely lucky''.
''I could've been down there and no-one would ever know - I would've disappeared off the face of the earth,'' she said.
''There were no tracks; no-one would've ever thought to have looked for me in that pond.''
Ms Kay said she knew the corner in question would be slippery that night as it was ''well known as a bad spot''.
She believed there was not enough grit on the road and urged the Waitaki District Council to address the problem.
