Luke Durbin, 19, was last seen in Ipswich on 12 May, 2006 after a night out in the town.
CCTV pictures show a Volvo 440 in the town centre at the time of his disappearance.
Suffolk Police have now issued pictures of the same type of vehicle in the hope they can trace the actual car's occupants or jog someone's memory.
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The move by the inquiry team comes on what would have been Mr Durbin's 29th birthday and follows the offer of a £20,000 reward for information, issued in May.
Det Supt John Brocklebank said: "We are researching the information provided [so far] to see if this can be developed but we haven't got the crucial piece yet - and we believe there are still those that may be able to help.
"We appreciate that this is nine years ago but you may be able to help us identify who was driving this vehicle that night."
The CCTV images show a white or silver Volvo on Orwell Place near the Eagle Street/Fore Street crossroads at 04:09 BST on Friday, 12 May, 2006.
Police said they had confirmed there was a Volvo 440 in the Ipswich area with the number plate M206 LYE at the time, but it was registered under a false name and address.
They are keen to hear from its owner or anyone who recognises this number plate so they can confirm whether it was the car in the CCTV images.
New photos of a car have been issued by police investigating the disappearance and suspected murder of a teenager.