BMW and Mazda top CO2-cutting chart
The cuts of 10% by BMW and 8.2% for Mazda relate to the average reduction in CO2 emissions for cars sold in Europe during 2008.
Not the whole story
However, Mazda's success is due to the fact that it has been slow to improve efficiency in the past, which has allowed the company to make such striking improvements during 2008.
BMW, on the other hand, has successfully cut its overall CO2 emissions by offering its Efficient Dynamics technology across its entire product range.
Progress in cutting emissions slowed dramatically at Fiat and Peugeot-Citroen, but both already have fleets that rank among Europe's cleanest and are close to meeting legally binding EU targets by 2015.
The report also reveals that nine out of Europe's 14 largest car producers achieved cuts of just 4% or lower.
The finer detail
The CO2 report analyses the strategies that carmakers are employing to bring down their average emissions.
Ford sold off its gas-guzzling Jaguar and Land Rover brands; that move alone accounted for over half of the company's average CO2 reductions.
The Volkswagen Group, together with Japanese hybrid manufacturers Toyota and Honda, made relatively poor progress because they offer the most fuel-efficient technologies as an option rather than across the range. The relatively small number of Bluemotion, Prius and Civic Hybrid sales in 2008 had a correspondingly low impact on fleet average emissions.
The BMW Group,, who recorded the biggest improvements for the second year running, offers its Efficient Dynamics technology across its entire product range.
The results in full
Ranked by progress in cutting CO2 emissions achieved during 2008:
1) BMW -10.2%
2) Mazda -8.2%
3) Hyundai -7.6%
4) Ford -6.7%
5) Suzuki -4.9%
6) Nissan 4.0%
7) Daimler -3.8%
8) VW Group -3.3%
9) Renault -3.2%
10) Fiat -2.9%
11) Toyota -2.4%
12) GM -2.3%
13) Honda -2.2%
14) Peugeot-Citroen -2.0%
Jos Dings, director of Transport & Environment said: 'The new EU law is already having an impact. Car makers can see how far they have to cut, and are changing their ranges accordingly.'