* CO2 from new cars fell 3.7 pct in 2010 - provisional data
* Average emissions now stand at 140.3 grams CO2 per km
* Average weight rises by 28 kg after falling in 2009
BRUSSELS, June 29 (Reuters) - The fuel efficiency of European cars advanced last year, with exhaust carbon emissions falling 3.7 percent, provisional European Union data showed on Wednesday.
The EU, home to 500 million people, has set a target for cutting average emissions from new cars to 130 grams of CO2 per kilometre by 2015.
Last year's improvements bring the average emissions of new cars to 140 grams, putting the EU on track to overachieve on a target that was set in 2008 despite heavy lobbying from car makers in Germany, France and Italy.
In 2009, car emissions fell 5.1 percent.
"These data show again that setting targets... stimulates the car industry to put greener cars on the market," said EU climate commissioner Connie Hedegaard. "These innovations also ensure Europe's car industry remains competitive in the changing global market."
The weight of cars rose by 28 kg in 2010, after falling in 2009, a trend that environmentalists blamed on increasing numbers of small sports utility vehicles (SUVs).
"That is no surprise," said Arne Richters at transport campaigners T&E. "EU rules favour heavier cars by allowing them to emit more CO2. The EU should be favouring more efficient saloons, estates and hatchbacks rather than encouraging gas-guzzling, tall and heavy SUVs."
Car industry group ACEA says cars with emissions below 120g per km now have a 29 percent market share.
"Most of the progress so far has been achieved through improved efficiency in the internal combustion engine," said ACEA spokeswoman Sigrid de Vries. "The next step is to ensure the market introduction of new breakthrough technologies -- and that is a significant step."
The report from the EU's environment watchdog, the European Environment Agency, showed the lowest average emissions from new cars sold in Denmark and Portugal, largely confirming a report in March.
Bulgaria, Denmark, Greece, Ireland, Latvia, Lithuania, Netherlands and Sweden recorded the largest annual reductions, of about 8 percent on average.
(Reporting by Pete Harrison, editing by Rex Merrifield)