The mishap took place while the family was going to Kota to attend a marriage.
The car overturned near Deva ka Kheda village on the highway, Assistant Sub Inspector Ramkishan said.
35-year-old Rakesh Joshi died on the spot, while Jivanram (69), Bhagirath Joshi (57), Ajay Vyas (14) and Ashish (11) were rushed to hospital, Ramkishan said.
Jivanram succumbed to his injuries during treatment, he said. He was driving the car at the time of the accident.