Porsche's congestion claims rejected

Porsche claims that it has unearthed a report proving that carbon dioxide levels will rise under new Congestion Charge proposals - but the report's findings have already been rejected by its own authors.

The new Congestion Charge rules come into force on October 27. All cars that emit over 225g/km of carbon dioxide will be charged £25 to enter the congestion charge zone, while cars that give off less than 120g/km will be exempt from the charge.

The report, commissioned by Transport for London (TfL) and carried out by the Environmental Research Group of King's College London, was only released after a specific request from Porsche, which is seeking to have proposed changes to the charge overruled.

Porsche claimed the research showed that, if the changes go ahead, CO2 emissions in outer London will increase from current levels to 182,000 tonnes by 2012.

This would mainly be caused by drivers travelling further outside the congestion charge zone to avoid it.

Porsche claimed its discovery of the report highlights that the changes to the congestion charge zone have been implemented without proper consultation.

However, Sam Beevers, who is head of the air quality modelling department at King's College, has since admitted that the report's findings were inaccurate.

He said: 'Through further discussion with TfL we now understand that the results contained in our draft reports to TfL in relation to traffic pollutants and CO2 need to be refined. This problem arose due to ambiguity in the assumptions used.

'As a consequence, we are currently providing TfL with revised assessments. These are likely to show that our estimates of the CO2 effects are broadly comparable with those that have been produced by TfL.'

TfL maintains that the changes to the Congestion Charge will cut CO2 emissions from cars travelling to and from the zone by up to 5000 tonnes in 2009.