European carmakers fear that many jobs will be lost and their brands will suffer if the European Commission opts this week for tough CO2 emission limits to be imposed on new vehicles.

Splits within the European Commission have burst into public with Günter Verheugen, the Industry Commissioner, briefing that there will be no legal limits and Stavros Dimas, the Environment Commissioner, giving warning that carmakers should expect a mandatory target for 2012.

The full 27-member Commission will take the decision on Wednesday, with the battle being seen as a test of the green credentials of José Manuel Barroso, the European Commission President.

Mr Dimas says that legislation is needed because manufacturers will fail to meet a voluntary target agreed in 1998 that average emissions should fall from 186g of CO2 per kilometre travelled to 140g/km by 2008-09 and 120g/km by 2012. The average for 2004, the latest made public, was 163g/km.

Mr Verheugen is arguing for an “integrated” approach with further voluntary targets backed by measures to improve tyre performance, highway design and traffic management across Europe. “Let’s not forget that luxury cars are one of the strong points of the EU’s exports,” he said. Some manufacturers fear that the worst-performing individual companies will be targeted. That could be bad news for some of the best-known British marques, such as Aston Martin and Land Rover.

• Senior executives in Britian and across Europe now claim that environmental protection is their top political priority, more than twice as important as promoting free trade and ahead even of promoting stable economic growth. The UPS Europe Business Monitor, which surveys 1,450 executives in seven countries, showed that they back a switch from fossil fuels to renewable energy and nuclear power.