A decision on whether to impose mandatory limits on the amount of greenhouse gases emitted by new car models will be made by the European Commission on Wednesday. The move follows the failure of voluntary targets.

The European Union's Environment Commissioner, Stavros Dimas, would like to see a new EU law requiring European, Japanese and Korean car makers to keep emissions from new passenger cars to an average of 120 grams per kilometre from 2012. Different sized cars will have different targets.

Cars [in the EU] currently emit an average of 160 grams of greenhouse gases for each kilometre they travel. In 1999, the EC recommended that European, Japanese and Korean car makers voluntarily limit their emissions to 140 grams per kilometre travelled by 2009.

The aim was to cut emissions from new cars in Europe to 25% of 1995 levels. But the EC says car manufacturers have only reached 12%, which is "not satisfactory".

Only Fiat, Citroen, Renault, Ford and Peugeot are on track to meet the target. Volkswagen - Europe's biggest selling car brand - was singled out for its poor performance in an October 2006 study (pdf) by the European Federation for Transport and Environment. The study said VW had improved its fuel efficiency at less than half the rate needed.

Slow progress
Fuel efficiency is improving very slowly, says Malcolm Fergusson, at the UK-based Institute for European Environmental Policy. But car companies are also selling more and more large, gas-guzzling cars.

The car makers say it is not their fault the targets have not been met. The European Automobile Manufacturers Association blames "strong customer demand for larger and safer vehicles and disappointing consumer acceptance of extremely fuel-efficient cars".

Reaching the 120 gram target "will require a rapid acceleration [in fuel efficiency] compared with the current rate, to the point that some doubt it is realistic," says Fergusson.

Road transport creates more than 20% of all carbon dioxide emissions in the European Union, with half of that coming from passenger cars. But even if the proposal is adopted on Wednesday, the legislative instrument needed to enforce it will not be in place for another year at least.