The impact "totally demolished" the small Mazda car, which had been travelling up to 80km/h at the time.
"She's a very lucky lady."
The falling power pole caused three more poles to fall onto the road, and the three vehicles which had been following the elderly woman's car were "encased" in a tangle of high-voltage power lines.
Although the woman's car also had lines draped across it, several young men managed to pull her from the vehicle.
She was taken by road ambulance to Hawke's Bay Hospital, where a hospital spokesman said she was in a serious condition yesterday. The trapped motorists waited in their vehicles for about an hour before the power supplying the lines could be shut off.
Chris Newrick, Hastings, said he had been driving his 1971 GT Falcon to join the Art Deco Weekend festivities when the lines fell on his car, trapping him and his wife, Amanda Holmes, who is six months pregnant. One of the power poles had fallen just metres from his car.
"I'm gutted. It's all right, because none of us were hurt, but the car's been hurt. It's going to need a repaint."
He said his wife had been distressed by the situation.
"She was very upset at the time - she was crying."
Barry Franklin, Dannevirke, had been following the elderly woman's car in his campervan when he witnessed the crash.
"It was a hell of a bang. The back of her car got up and swung right around. Then the pole fell down exactly where she would have been if she hadn't swung around. She was very, very lucky."
Mr Farquharson said the road was closed with traffic diversions in place for about two hours after the 2.15pm crash.
Unison Networks customer relations manager Danny Gough said the fallen poles had meant a loss of power for about 640 customers.
Power was restored to 500 customers after about an hour and to everyone affected by about 9pm on Saturday.