Those killed were all the occupants of the car, a Maruti Suzuki Ertiga, which was on its way to Ahmedabad from Vadodara.
While eight people were reportedly killed on the spot, two others died while being taken to hospital.
According to reports, the Maharashtra-registered truck was parked on the extreme left lane of the expressway after it encountered a mechanical fault.
The truck was on its way to Jammu from Pune in Maharashtra.
As per the police, the car passengers hailed from different cities of Gujarat, including Vadodara, Nadiad, and Ahmedabad, and only four of the victims were identified so far.