A woman who claimed a car she was test driving was stolen by two men who flagged her down has been arrested.
The 26-year-old told police she was ordered out of the black BMW 1 Series model in Llandarcy, Neath Port Talbot.
South Wales Police said the woman had been held along with a 29-year-old man on suspicion of conspiracy to steal, wasting police time and perverting the course of justice.
Detectives said they were working on the basis the incident did not happen.
The woman had claimed she was stopped by two people in a Ford Focus on Sunday 3 April, who then drove off in the BMW.
The alleged theft was said to have happened near a gas distribution depot on the B4290 as the woman was returning the vehicle to a car showroom on Fabian Way, Swansea.
A third person was said to have driven off in the Ford Focus.
The woman, who gave descriptions of the first two alleged assailants, was said to have been left "shaken" by the incident.
Det Ch Insp Simon Davies of Neath Port Talbot CID said: "The incident as reported was very unusual but it had to be fully investigated."
The man and woman who have been arrested were being questioned at Neath police station.
Anyone with information which might help the investigation should contact South Wales Police on 101 or the independent charity Crimestoppers on 0800 555 111.