Avon and Somerset Police have appealed for witnesses describing the death as "tragic and brutal".
Detective Chief Inspector Simon Crisp said: "Investigations continue into Catherine's death and we are still working to piece together her life.
"I am particularly keen to appeal to the driver of a dark coloured people carrier that we were believe was travelling from Ilminster to Taunton, past the scene about 6.10am on Wednesday. We believe the car braked at the point of the car fire.
"I would also like to speak to anyone who saw a white transit or smaller van or was in a white transit or smaller van that was parked in the vicinity of the scene.
"My final appeal is to members of the public who saw anyone in the area wearing a high visibility jackets, these people may have information that is significant to this investigation."