The detective in charge of the hunt for the killer is sure the person who shot Mr Hardwick dead knew who they were murdering.
Det Supt Bob Bridgestock said: "All our inquiries so far show that Mr Hardwick was a hard-working man who had no known enemies, or involvement in activities that would make him a target.
"Yet he became one. We still need to know why."
Fifty-year-old father-of-two Mr Hardwick, from Wibsey, Bradford - who married his second wife, Lynne, just six months before his death - was shot twice at close range while repairing a puncture on his car at his workplace, Huddersfield Car Electrical Services in Colne Road.
His car tyre had been deliberately punctured with a sharp object.
Police believe the killer may have done this to force Mr Hardwick to stay alone at work to fix it after his colleagues left at 5.35pm on November 21.
His cashcard was stolen and used at a cashpoint at the Asda store on Bradford Road, Brackenhall, at 6.15pm that evening to steal £350 from his account.
Det Supt Bridgestock said: "It was not a case of mistaken identity. Mr Hardwick was the killer or killers' target. He was shot twice. No other injuries were present, and neither had there been any attempt to restrain him.
"The killer could have clearly seen Mr Hardwick's face - and may even have spoken to him."
A criminal profiler has been drafted in to look closely at the circumstances of the murder, to see what they indicate about the kind of person who committed it. But police remain puzzled over the motive.
Although a broken-heart necklace was stolen, along with a grey popper purse and a wallet containing Mr Hardwick's cashcard, police are keeping an open mind.
Det Supt Bridgestock added: "Was there something more than robbery to this crime? "
He remains convinced that someone has a vital piece of information that could cause all the other evidence already gathered to fall into place.
He said: "There are, I am sure, people with information about Mr Hardwick and his death who have not come forward. That information may be vital to the inquiry."
He added: "The initial and subsequent Press conferences and releases have not brought forward a great deal of information.
"However, as in all investigations, it is the quality of the information that counts.
"The team is looking very closely at every scrap of information that comes in, and we are receiving the results of forensic evidence all the time."
Police have talked to 900 people, ranging from Mr Hardwick's family, friends and customers through to criminals who have been known to rob garages or use guns.
"Somebody out there knows something," said Det Supt Bridgestock.
Contact the murder incident room in confidence on 01484 436702 or Crimestoppers on 0800 555 111.