French, Italian and Japanese car makers have extended their lead over German rivals in the race to deliver low emission vehicles.

While their rivals have cut the average emissions of carbon dioxide from their new cars, German car makers actually increased emissions from their new cars by 0.6% on average.

According to figures from environmental lobby group Transport and Environment, Japanese car makers also made significant progress in 2006, achieving 2.8% cuts on average.

Toyota made the biggest improvement of any major car manufacturing group with the average vehicle sold in 2006 emitting 5% less CO2 than the previous year.