At around 9.30pm on Thursday (13/5), a red Vauxhall Astra and a black Jaguar XFS were involved in a collision on the M4 eastbound between junctions 12 and 13.
The driver of the Astra, a woman in her fifties, sadly died at the scene. Her next of kin have been informed and are being supported by specially trained officers.
The driver of the Jaguar was uninjured.
No arrests have been made.
Investigating officer, Detective Sergeant Tony Jenkins, of the Joint Operations Roads Policing Unit, said: “We are appealing to any witnesses to this incident to please come forward.
“I would also ask motorists with dash-cams to check any footage to see if they may have captured the collision or anything prior to it taking place in case it could assist with our investigation.
“Anyone with information can contact police by calling 101 or making a report online, quoting reference 43210206727.”