"The car started to get foggy and the weather was just horrendous so I was concentrating on my driving."
Paula said the woman's attitude suddenly changed and she became verbally abusive.
"I started to feel quite afraid so I pulled over and had to physically push her out of the car."
As the lady was getting out of the car she said "You stupid b****, I've got your money", and Paula realised the woman had taken her wallet.
She drove straight to the police station.
"The police were very good. They showed a great deal of compassion and even made me a cup of tea."
Whanganui crime prevention manager Senior Sergeant Andrew McDonald, described the theft as a "heartless act".
"It was a heartless way of taking advantage of the trusting and generous nature of a senior person. It was an extremely low thing to do," McDonald said.
McDonald said he was not aware of other such thefts and hoped it did not become a trend.
"We will be reviewing CCTV footage and investigating further but there are no suspects at this stage."
McDonald said police didn't want to stop acts of kindness but warned people to be conscious of their valuables if offering strangers a lift.
The offender is described as a female, about 50 years of age, of thin build with fair skin.
Anyone with information can contact Whanganui Central Police Station on (06) 349 0600, or information can be given anonymously to Crimestoppers on 0800 555 111.