Calls began coming in Sunday afternoon from witnesses, some of whom trailed the car into the provincial capital city, Victoria Police Constable Kris Rice told the Victoria Times-Colonist.
"There were some reports that they seemed to be wanting attention from other drivers as they engaged in sexual acts," he said.
The owner of the vehicle was traced from the license plates and officers went to that address to await the car's return, Rice said.
On arrival, only one of the women was inside with the male driver, both in their 20s, the report said. The unidentified driver said he had dropped the other woman off.
"Both were determined to be in the nude," Rice said.
The woman was taken to a hospital for psychiatric assessment, while the driver will likely only face such charges as driving without due care and attention, as police didn't witness any sexual acts, the report said.