Cars sold in Europe last year reduced carbon emissions slightly, with manufacturers managing to achieve an average improvement of 1.7 percent, according to a new report.

Green campaign group Transport & Environment, the authors of the report released on Tuesday (26 August) tracking the progress of Europe's major car manufacturers have made in reducing CO2 emissions, welcomed the reduction.

The group celebrated the fact that the companies had beaten their all-time nadir last year of an improvement in fuel consumption of just 0.7 percent, but warned that such figures showed the firms are still not on track to meet climate targets.

"The lack of progress was, again, explained to a large extent by the lack of progress in cutting weight. In 2007, cars again became 10 kg heavier...Heavier cars use more fuel," reads the study. In a turnaround of its fortunes however, BMW showed a marked improvement in the fuel consumption of its fleet, with the average new car sold by the German firm in 2007 consuming some 7.3 percent less fuel than in 2006.

Jos Dings, director of the environmental group said: "With the threat of legislation looming, BMW has shown that even premium carmakers can seriously reduce CO2."