Prepared by Ricardo for the Low Carbon Vehicle Partnership, the report found that some of the CO2 savings made during the use of low-carbon vehicles is offset by increased emissions created during their production, and to a lesser extent disposal. However, it says that, overall, electric and hybrid vehicles still have lower carbon footprints than normal cars.

As an example, a typical medium sized family car will create around 24 tonnes of CO2 during its life cycle, while an electric vehicle (EV) will produce around 18 tonnes over its life. For a battery EV, 46% of its total carbon footprint is generated at the factory, before it has travelled a single mile.

The LowCVP says that the study demonstrates the increasing importance of measuring whole-life carbon emissions to compare vehicle performance.

Greg Archer, LowCVP managing director, said: 'This work dispels the myth that low-carbon vehicles simply displace emissions from the exhaust to other sources. However, it does highlight the need to look at reducing carbon emissions from vehicles throughout their lifecycle.

'The automotive industry is already taking positive steps to address this issue – the recent announcement by Toyota of a solar array to provide electricity to power the hybrid Auris production facility and wind power at the Nissan LEAF plant are excellent examples of this.'

The report also indicates that lifecycle carbon emissions for mid-sized petrol and diesel vehicles doing a similar lifetime mileage are almost identical – the greater efficiency of the diesel being offset by high production emissions. It also highlights that some regulations designed to improve recyclability, safety or reduce air pollution can increase carbon emissions in production or use.

Ricardo chief technology & innovation officer and chairman of the LowCVP, Prof Neville Jackson said: 'Life cycle analysis is still in its infancy, with little defined process and standards. The Low Carbon Vehicle Partnership report is an important contribution to this type of analysis and highlights the need to work toward a common methodology and approach to deliver consistent and robust life cycle data on CO2 emissions.'