A couple engaged in a relationship inside a vehicle died from carbon monoxide poisoning.

The couple found naked in a car in Germany is believed to have died from asphyxiation after starting the engine to warm up while engaging in sexual activity.

The lifeless bodies of a 39-year-old man and a 44-year-old woman were discovered by the police in a locked garage in the city of Bottrop, located in North Rhine-Westphalia, Germany.

According to the police, the naked couple, whose names have not been disclosed, started the car's engine to warm up and apparently died from lack of air as a result.

No one had noticed that the car's engine had been running for hours behind the metal door of the garage, which is located behind a commercial building.

The police opened the garage door after the man's family reported him missing for several days.

Meanwhile, city officials had also launched an investigation into the woman's sudden disappearance.

The police stated that there were no signs of foul play, but forensic scientists are making every effort to determine exactly what happened. Tests are being conducted to determine the carbon monoxide levels in the couple's blood.

"To eliminate all doubts, the prosecutor ordered an autopsy to be performed on the bodies."