BUKIT MERTAJAM - A decision to take a nap with the car engine left running proved fatal for two men at the south-bound Juru rest area of the North South Expressway.
Rizuan Ismail, 35, who was at the driver's seat and Ong Cheng See, 39, on the front passenger seat, were found dead inside the four-wheel-drive parked at a petrol station there.
The duo, said to be working as oil rig contractors, apparently decided to take a nap.
They were spotted sitting motionless inside the vehicle at 7.30pm Friday by a customer who alerted the staff on duty.
Attempts to wake them up by shaking the vehicle and knocking on the windows proved futile.
The locked doors had to be pried open by firemen who arrived within minutes after a distress call.
Penang police chief Senior Deputy Comm Datuk Wira Abdul Rahim Hanafi said the case has been classified as sudden death.
"There were no signs of injuries on both men.
"We will study the CCTV footage obtained from the petrol station," he said, adding that Rizuan was from Kedah while Ong was from Malacca.
A post-mortem showed that the duo died of carbon monoxide poisoning.