A 40-year-old man was arrested today by detectives investigating the murder of 13-year-old Milly Dowler.
The suspect, from west London, was being questioned today over the disposal of a red Daewoo Nexia car, Surrey Police said.
Investigators believe prime suspect Levi Bellfield used the car to transport Milly's body from Walton-on-Thames in March 2002.
A Surrey Police spokeswoman said: "A 40-year-old man from West London was arrested by Surrey Police at 10am this morning after voluntarily attending a police station.
"He is being questioned about the potential disposal of a red Daewoo Nexia car, which police have appealed for information about as part of their investigation into the murder of Milly Dowler."
It is understood that the man is not suspected to be directly involved in Milly's murder and is unlikely to be charged with any criminal offences today.
But detectives want to question him about the fate of the car which is central to the ongoing unsolved murder inquiry.
The car was captured on CCTV in Walton-on-Thames minutes after Milly disappeared and Bellfield has since admitted driving it.
he death of Amanda Dowler, known to her family and friends as Milly, remains one of Britain's most notorious unsolved crimes.
She vanished while walking home from school in Walton-on-Thames, Surrey, on March 21, 2002.
Six months later her skeletal remains were found 30 miles away by mushroom pickers in Yateley Heath, Hampshire.
Officers have been painstakingly building a case against Bellfield since he was arrested by the Metropolitan Police in November 2004 over other matters.
Bellfield, 41, was told last year that he will die in jail after he was found guilty of murdering students Marsha McDonnell, 19, and Amelie Delagrange, 22.
He was also convicted of the attempted murder of schoolgirl Kate Sheedy, 18. All of the women were attacked near bus stops in south west London.
The former nightclub bouncer and wheelclamper was arrested and interviewed over Milly's death four years ago.
Officers believe they have compelling circumstantial evidence which links him to the appalling crime and plan to interview him again.
They want to trace the red Daewoo Nexia, then owned by Bellfield's girlfriend at the time, Emma Mills, because it may contain key forensic evidence linking him to the murder.
In a newspaper interview earlier this year, Bellfield admitted driving the car on the day in question.
He said it was sitting low on its suspension, something that further aroused police suspicion, because he was transporting tools and building gear.
The vehicle was reported stolen from a pub car park in Hounslow several days later and has not been seen since.
In their hunt for the car, police searched 35 miles of waterways and 40 other water sites, including reservoirs and lakes in Surrey and neighbouring counties.
Detectives believe it is likely that one of Bellfield's many contacts in the motor trade arranged for it to be crushed by a scrap dealer.
A similar red car also features in another major line of inquiry sparked by what may have been an attempted abduction the previous day.
The family of a 12-year-old schoolgirl told police a man in a red car offered her a lift home in Shepperton, less than three miles from Walton-on-Thames.