Police in Malaysia have clamped down on a promotion in which car wash customers were offered free sex after their ninth visit.The unusual reward programme was born out of a partnership between a car wash and a massage parlour, police told the Malay Mail.Officers discovered the hook up when they raided the massage parlour, in Kuala Lumpur, and found several customers had reward cards for the car wash."To get the extra offer, customers had to send their cars for washing nine times within a certain period," Officer Emmi Shah Fadhil said. "The tenth car wash entitled them to free sex."Four men suspected of running the massage parlour and nine Vietnamese women, believed to be prostitutes, were arrested.