A video published on YouTube shows a driver claiming he can operate his car safely and use his phone at the same time - before crashing into the car in front.
In the video, a cyclist believed to be Dr Dave Brennan, caught up with the driver on the A739 Switchback Road, between Bearsden and Glasgow.
He questioned the driver, asking "can you drive safely with your mobile phone?”, to which he was told "yes I can."
When Brennan caught up with the same driver further down the road, the man crashed into the back of the car in front.
In the full length video, it is observed that the driver had stopped using his phone when he crashed into the car ahead of him.
The video is captioned, and the rider adds: "I hung around and offered to be a witness, to the driver in front, they were happy to just sort it between them. The mobile phone driver was more sheepish after that."
Despite the threat of three points and a £200 fine, as well as an increased likelihood of being refused for insurance, seeing drivers on their phones at the wheel isn't uncommon.
Research by the AA shows that a driver's insurance can increase by 40 per cent if they've been caught using a phone whilst driving, with the price increase remaining for five years.
It also found that four out of nine insurance firms, when questioned, said they would refuse to insure a driver with a CU80 mobile offence.
