SOUTH WALES Police is appealing for witnesses following a collision at the Coryton Interchange in Cardiff shortly before 3am today (Friday, April 26).
The driver of a silver-coloured Citroen C3 SX, a man in his 70s, sustained serious injuries in the incident.
He is being treated at the University Hospital of Wales in Cardiff. The female passenger was also taken to hospital.
The vehicle had been travelling westbound along the M4 before leaving the motorway at Coryton.
Officers have urged anyone who witnessed the collision, including capturing it on their dash-cam, or who may have any other relevant information such as the manner of driving on the M4 prior to the collision, to contact the Serious Collision Investigation Unit via 101, quoting occurrence 1900148554.