Police are appealing for witnesses to come forward after a serious crash closed a stretch of the M5 motorway in North Somerset for more than an hour on Saturday afternoon.
Officers want to hear from anyone who may have seen a red Ford Escort being driven erratically southbound between junction 19 at Portishead and junction 21 at Clevedon.
The Escort was seen to undertake other vehicles and switch lanes to weave through the traffic, according to Avon and Somerset Police.
The car was then involved in a collision with another car and ended up on its roof.
Police said the driver, a man in his 60s, and his teenage female passenger were not seriously injured.
The force's roads policing unit are keen to hear from anyone who saw the Escort before the collision, and particularly want to hear from people in a red or maroon Peugeot 306 estate that was driving just ahead of the Escort before it crashed.
Anyone with information should call the roads policing unit at Almondsbury on 101.