The incident took place in Charbhuja police station area when the family was on its way to Vadodara from Jaipur in the car, they said.
Amrit Lal Modi (69), Suman Modi (63), Alkesh (37), Teenal (33) and Dhanvi (25) died on the spot, the police said, adding a girl was also injured in the accident who has been admitted to a hospital in Rajsamand.
Post mortem will be conducted after family members of the victims reach the hospital, they said.