The incident occurred last evening when the car, fitted with a gas cylinder caught fire near Alem town, Additional District Magistrate Pratap Singh Bhadoriya said today.
The group was returning to Loni in NCR after attending a marriage function from Ghasoli village in the district.
Earlier, police had said that seven persons, including four children, were burnt alive and six others injured in the mishap. However, today they said 14 people have died.
The six injured have been admitted to a hospital in Delhi, police said.