The unidentified body was discovered in a small car park area between Roe Green and Wallington on Tuesday evening.
A police “major crime unit” is calling for witnesses who may have seen a “distinctive” white Ford Fiesta with blue stripes being driven in the Cat Ditch Road area between 6pm and 8.30pm on Tuesday.
Detective Inspector Justine Jenkins, from the Bedfordshire, Cambridgeshire and Hertfordshire Major Crime Unit, said: “We are working hard to identify the woman and trace her family who will be supported by our specially trained officers.
“As part of our investigation we would like to speak to anyone who saw the pictured vehicle in the Cat Ditch Road area. Please take a look at the image and get in touch if you saw it.
“We believe there a few vehicles of this type in the local area and so I would like to stress that we know the owner of this particular vehicle.
“I particularly want to ask anyone who was driving in the area with a dash cam to check their footage and get in touch if you spot the vehicle.
“If you have any other information that you think may help our investigation, please don’t hesitate to get in touch.”