Though no suicide note has been found, but police suspects the reason of suicide could be the resistance from their families as they were unhappy with their relationship on religious grounds.
Residents alerted the police after seeing the car's engine running and its lights on. Police broke the car's door and found Mr Khan and Ms Negi unconscious inside. Both were declared brought dead at hospital.
Preliminary investigations revealed that Mr Khan, a resident of Mulund, and Ms Negi, who lived in Navi Mumbai, were in a relationship for the past four years. They wanted to get married but their families were reportedly against the relationship, a senior police official said.
The car in which the couple was found dead belongs to Mr Khan, the officer said, adding that further investigation is on.
(With Inputs From PTI)