A tag attached to the keys bears the code T144213
Detectives investigating the murder of a Wiltshire woman whose remains were found close to the M5 received more than 200 calls after a TV appeal.
During the BBC's Crimewatch programme Melanie Hall's parents spoke of their 13 year ordeal and hopes that their daughter's killer would be caught.
It was also revealed that three Ford keys, possibly from a Transit, Fiesta or Escort, were found near the body.
Police are now working with Ford to identify the vehicle.
Det Supt Mike Courtiour said the keys, which have been dated to 1996, the year Ms Hall vanished, may be a significant find.
"How did those keys get there? Are they connected or is there an innocent explanation.
"They've been there for some time and were found close to the body.
"There's two sets of ignition keys and a red "programming" key bearing a code tag T144213."
Mr Courtiour also revealed police had received a lot of calls offering information about the blue 4mm polypropylene rope which was wrapped around the body and used to tie the bags up.
He said despite an excellent response to the appeal he believes someone close to the killer may have vital evidence.
"Someone very close to that person has stayed silent for 13 years.
"Examine your conscience and come forward and help us solve this crime," he added.
Melanie Hall, 25, went missing after a night out in Bath on 9 June, 1996.
Black bin bags containing Ms Hall's bones were found by a workman at the side of the M5 near Thornbury in South Gloucestershire, on 5 October.
A reward for information leading to the arrest and conviction of Ms Hall's killer has now increased to £20,000.