NSW Police are investigating the discovery of a body in the boot of a car in Sydney's west.

A member of the public made a parking complaint about the car near Rookwood Cemetery in Lidcombe on Sunday morning.

Local residents said the car was damaged and had aluminium foil over its number plates.

Detective Inspector Paul Arnold said the body of a man was found inside the car and could have been there for a couple of weeks.

"Police opened the vehicle and were subject to an overpowering smell," he said.

"As a result of this police opened the rear of the vehicle, being the boot, and located the body inside the boot."

Police, forensics and homicide squad officers were at the scene.

Detective Inspector Arnold said a post-mortem examination will be held at Glebe on Monday morning.

Police have called for anyone who noticed the green Honda Accord parked on East Street to contact Crime Stoppers.