The 24-page guide, called 'Driving At Work' and produced by the Department for Transport, was released last month and identified almost 100 areas fleet decision-makers need to consider to ensure drivers are safe on the road.
But while broadly welcoming the guidance, some industry experts are concerned that certain recommendations will be ignored because they are not backed by legislation.
Tom Arnold, chief executive officer of fleet management software company WS2, described the guide as an 'extremely vital document' but added: 'Many of the guide's recommendations are not legal requirements and could gradually move to the bottom of busy human resource or fleet manager 'to do' lists.'
The Association of Car Fleet Operators (ACFO) said fleet decision-makers who ignore the guidance do so at their peril, but it too voiced concerns that it is not backed by legislation.
Director Stewart Whyte said: 'While it provides a useful checklist for all fleet operators to help them put in place a risk management strategy it falls short of being the highway code it should be.'
Peak Performance managing director James Sutherland said the warning to companies was the clearest yet.
'Companies should now clearly understand if they do not have in place procedures and practices to ensure they have assessed the risk associated with that activity and taken steps to minimise it, they could face the stiffest possible penalties arising from any form of accident or incident caused by their employees.'
And Richard Schooling, commercial director of leasing company Alphabet, suggested a national fleet safety accreditation scheme be created so that firms that are fully committed to best practice in risk management can be recognised.
'Such a scheme would also highlight the role that trained and experienced fleet personnel play in improving levels of fleet safety,' Schooling added.
The new guidance was also welcomed by motoring organisations.
Andrew Howard, head of road safety at the AA Motoring Trust, said: 'With up to a third of road traffic accidents occurring during work-related journeys any effort to reduce this total must be embraced by companies and their staff.'
Fleet management company Interleasing is calling for a balance of responsibility between employers and employees when it comes to managing risk on the road. It has launched its own driver safety section on its website at www.interleasing.co.uk.
Diarmuid Fahy, accident services manager at Interleasing, said: 'The recent corporate manslaughter legislation has brought the focus firmly on the employer and while this is right, unfortunately there is only so much a fleet manager can do.'