A pensioner suffering early-stage dementia probably spent two weeks trapped on farmland in his broken-down car before dying of pneumonia, an inquest heard.
John William Davies, 78, suffered hallucinations the night before he disappeared and had probably become disorientated when he became stuck in a remote country lane.
There was evidence that he was still alive a day or two before his body was found in the Nant-y-Moch area of mid-Wales.
Mr Davies had been missing for 15 days when he was found in his Rover on farmland between Caer Arglwyddes and Blaen Clettwr fawr, Nant-y-Moch, by Alan Lloyd Williams who was out moving sheep.
Police had been searching for Mr Davies, a grandfather of five and former policeman, since he disappeared from his home at Ty Mawr Y Llan, Llancynfelin, on Monday, 12 March.
The inquest was told that he had been having hallucinations the night before he went missing and that could have been a sign of dementia, which caused him to get lost or disorientated.
Ceredigion Coroner Peter Brunton said there was also evidence to suggest Mr Davies died just days before his body was found.
The cause of death was found to be bronchopneumonia, chronic obstructive pulmonary disease, dementia and ischemic heart disease.
Mr Davies' wife, Margaret, said he had been in good spirits before he disappeared, but suffered from hallucinations the night before.