Sir David said police authorities' own fleet managers must also prove they can compete with the best suppliers in the private sector, but said leasing companies wanting police fleet business had to demonstrate they were the better option.
'If outside suppliers can prove they can manage our fleet business how we want it managing and can get involved in the operational side of policing then great, but can they?' he said. 'If they can do that – then why not? But I think it is right that our fleet managers should prove that they can do it better.'
Outsourcing has become a topic of fierce debate among police fleet chiefs, following the decision of the Metropolitan and Nottinghamshire police forces to outsource their fleet operations to Venson.
Speaking at the National Association of Police Fleet Managers' Conference and Exhibition in Swindon, Sir David also urged police fleet managers to become more involved in the operational side of policing so they become better briefed on which vehicles to provide for certain incidents.
'If an officer approaches you and says he wants a Ford Transit ask him what he wants a vehicle for and then tell him what sort of vehicle he should have. You wouldn't contact your IT department and tell them the model of computer you want,' he said.
And he questioned why forces could not have one or two models for typical police duties.
'We could get them cheaper and with all the equipment in,' he said. 'It's just an idea but we must ask ourselves questions all of the time. We should always look at what we do and how we do it.'
At last year's conference, the head of ACPO's procurement committee savaged the idea of public/private 'outsourcing' initiatives for police fleets.
Ian Readhead, deputy chief constable of Hampshire, claimed outsourcing lacked contact with police officers on the front line and compromised police fleets with decisions based on minimum contract obligations.