The debate on vehicle labelling follows a 1999 EU Directive which requires all cars in showrooms to display labels describing their carbon dioxide emissions and fuel consumption.
The Government's Cleaner Vehicles Task Force and its Advisory Committee on Consumer Products and the Environment have both called for a comparative label using ratings from A to G - already familiar from energy labels on household appliances (ENDS Report 309, pp 28-29 ).
They are unhappy with the motor industry's existing labelling scheme, introduced in 2000, which presents information in absolute terms only. Initially, their advice was rejected by the Department for Transport, which had been leaning towards a labelling scheme linked to CO2 emission bands in line with the existing graduations in vehicle excise duty. But the Department has recently shifted its position.
In January, the DfT submitted a report on the effectiveness of the UK labelling scheme to the European Commission, as required under the 1999 Directive. The submission admitted that the UK label has been "not very successful".
The Department now wants to switch to an A-G colour-coded label which bands vehicles according to their absolute CO2 emissions "as soon as possible". It points out that five different models of the Ford Focus would fall within five different bands - undermining arguments that such a system would not differentiate between similar vehicles.
But the DfT "understands and agrees with the arguments of the car industry that it would be very much preferable to have a common EU-wide system."
Dismayed at the delays in developing an improved scheme, the NSCA has written to the DfT urging it to introduce a revised label unilaterally. "
Agreement on a common EU label is at least four years away, during which time more than ten million new cars will have been sold in the UK," the association said.
The NSCA claims that motor industry representatives on the Low Carbon Vehicle Partnership, a Government advisory body, are blocking the idea.
"It is a matter of regret that, apparently due to car industry resistance, the LCVP was unable to reach agreement," the NSCA says in its letter. "Paradoxically, the first major policy influence of the LCVP has been to undermine a useful initiative."
"The depth of opposition to labelling suggests that car makers are worried that it might make a significant difference to market share, deterring consumers from buying energy-inefficient models."
According to NSCA policy director Tim Brown, some manufacturers - particularly those developing hybrid electric vehicles - hope that labelling will boost sales of cleaner models. But they are reluctant to break ranks with rivals who are worried that labelling could undermine existing product ranges by prompting consumers to downsize to smaller vehicles.
Both the DfT and the Environment Department (DEFRA) back a UK label, while the Treasury is keen to link it to vehicle taxation bands, said Mr Brown. But the Government is reluctant to press ahead with a revised UK label without the support of the LCVP, which has "kicked the whole idea into the long grass".
Paul Everitt of the Society of Motor Manufacturers and Traders, who chairs the LCVP's passenger car working group, said that the disagreement is on timing rather than substance. The LCVP needs to know how long it might take to introduce an EU label before it can decide whether a UK label might be a good idea, he said.
If it was not expected for around five years there would be scope for introducing a revised UK label first. "But I would find it bizarre if the Government pursued a course of action that could be subject to revision in a relatively short period of time," Mr Everitt said. "Consumers need a coherent, consistent label and it doesn't help if you chop and change the method of presentation."
The DfT told ENDS that it is looking for "definite support" from the LCVP. But in a reply to the NSCA, Transport Minister David Jamieson argued that it was "wrong...to suggest that the lack of a unanimous steer from the LCVP on car labelling has in any way undermined the Government's position."