The driver of the blue Citroen Picasso has been arrested following the incident in Ynyscynon Road, Trealaw, Rhondda Cynon Taff at 07:45 GMT Sunday.
Two men who police believe were travelling behind in a grey Citroen Picasso were also arrested.
The road was closed for six hours, with the passenger cut from the wreckage and taken to the Royal Glamorgan Hospital.
Police have appealed for witnesses.
A car crashed into six parked vehicles before overturning, leaving a woman passenger seriously injured.