The incident happened on Ennersdale Road at 5.05am today (Wednesday 27 June).
A man in his 70s was approached by a man after parking his car and threatened with a firearm.
The suspect took the victim’s car keys and left the scene in the vehicle in the company of a woman.
The offender made off towards Norton Road.
Detective Constable David Moorman from Nuneaton CID said: “Fortunately the victim wasn’t hurt but this was a terrifying incident for him.
“After recovering a magazine at the scene we believe the weapon used was a BB gun rather than a genuine firearm. However, the victim wasn’t to know this at the time and as you would expect he has been left badly shaken.”
Anyone with information is asked to call 101 quoting incident 26 of 27 June 2018 or the independent charity Crimestoppers anonymously on 0800 555 111.