A BLUE Ford XR6  could help police find who killed schoolgirl Tiahleigh Palmer, 12, whose body was found on a Gold Coast river late last year, after disappearing a week earlier.

Police say they have seized the 2009 sedan as part of its ongoing homicide investigation.

They are asking anyone who saw a similar car near the Pimpama area around October 30 last year to contact Crime Stoppers.

Detective Inspector Mark White said the car's owners were not suspects but "several persons of interest had been identified".

Det Insp White said the investigation was a top priority for police, with 20 investigators still on the case.

"The investigation's been going on for almost 11 months and the investigators involved are relentless in identifying those persons who are responsible," he said.

"As part of our investigation, which has been very broad and very protracted, we've made some progress in the last couple of weeks and as a result we've seized a vehicle as part of the investigation."

A $250,000 reward and immunity for anyone other than the main offender remains on offer, if they can supply information that leads to prosecution.