Their arrests come after two other suspects were released on bail following questioning on suspicion of conspiracy to murder.
Gloucestershire Police said a 53-year-old from Cheltenham and a 46-year-old from Cinderford had now been arrested on suspicion of the same offence.
Shaun James, 32, is believed to have been kidnapped before being run over.
His body was found with multiple injuries in Steam Mills Road, Cinderford, on 15 December 2002.
Detectives reopened the case last December as a murder inquiry.
A further two men have been arrested over the murder of a builder in the Forest of Dean in 2002.