Christopher Colegate, 69, was found in the road at the junction of Heath Avenue and Darby's Lane in Poole, at about 19:30 GMT on Friday 13 December.
He suffered significant injuries and later died at Poole Hospital.
Despite numerous appeals and rewards of £11,000 being offered, the driver of the car has never been found.
Dorset Police have renewed their appeal for witnesses.
Officers believe a light-coloured VW Golf Mark 4, made between 1998 and 2005, was involved in the collision.
Mr Colegate, from Poole, walked with a "distinctive stoop" and used two walking sticks.
Inspector Matt Butler, of the Dorset Police traffic unit, said: "We still do not know exactly what happened to Mr Colegate.
"We know that a number of cars were in the area at the time of the collision.
"Some we have traced but we have not been able to identify a Golf driver that travelled along Heath Avenue toward Wimborne Road at around the time of the incident."
Dorset Police and Crimestoppers are still offering a £10,000 reward, while Oakdale Conservative Club, which Mr Colegate regularly attended, has offered an extra £1,000.

The bank said that "due to changes in commercial priorities" it would not sponsor the event beyond 2016.
It has sponsored the event, which features the top eight men's players in singles and doubles, since 2009 when it moved to London's 02 Arena.
Barclays has also dropped sponsorship of the Premier League and London's "Boris bikes".
A spokesman said the bank was going through a period of change and it was re-assessing the way its portfolio of sponsorships worked for the company.
The bank has not disclosed the value of the tennis deal.
Separately the Daily Mail reported that the World Tour Finals would remain at the 02 Arena until at least 2018. There had been speculation that it would move elsewhere - with interest from North America and Abu Dhabi.
This year's event takes place from 15-22 November.
A hit-and-run driver who fled a collision in which a man was killed in Dorset is still being hunted a year on.
[NEXT_CONCEPT]
Barclays Bank is to end its sponsorship of the ATP World Tour Finals tennis tournament.