In a bizarre crash, a car drove under another parked vehicle outside the Hyatt Regency Sydney hotel in Sydney's CBD on Thursday.

A Subaru mounted on top of a Porsche outside the Hyatt Regency Sydney hotel on Sussex Street on Thursday morning.

A man was trapped after an orange Subaru was left balanced on top of a Porsche Carrera at the hotel in Sussex Street about 8.20am, a police spokeswoman said.

A valet was trying to park the Porsche when the crash occurred, Hyatt Regency's director of sales and marketing Matthew Talbot said, adding the valet was not injured.