The driver of a German registered car that crashed near Stroud is being urged to contact police.
The black Alpha Romeo came off the A4173 on Wednesday near the Edgemoor Inn, crashed through a fence and onto an embankment.
No other vehicles were involved.
Emergency services were called and the road was closed for more than seven hours until early on Thursday.
A 20-year-old man from Stroud was found in the car and is believed to have been a passenger in the vehicle.
He was taken to Cheltenham General Hospital and kept in overnight for observation.
Police are appealing for witnesses.