Police investigating the death of university graduate Catherine Wells-Burr want to speak to any motorists who may have driven past her burning vehicle on Wednesday morning.
Detective Inspector Simon Crisp said: "We know that there were many motorists that passed the site of this crime on Wednesday morning, and those people may have information that could help us.
"I would ask that you come forward and speak with us no matter how small you think your information may be.
He added: "It is also important that we speak with anyone who may have been in the area between 3am and 6am on Wednesday, using the roads between Chard and Ashill.
"Did you see a red Ford Focus, 5 door hatch back that may have been in company with another vehicle? If you did, please contact us."