Britain, France and Germany will press Europe's motor industry this week to accept tougher standards on emissions from new cars by the end of the next decade to promote a dramatic shift towards electric vehicles.

Gordon Brown, Nicolas Sarkozy and Angela Merkel want the EU to set a target for C02 emissions close to 100 grams a kilometre by 2020 compared with the current target of 120 grams by 2012-15.

Some industry executives say that the new target would be impossible to achieve with conventional petrol/diesel engines and would mean a leap towards "green" technologies such as all-electric vehicles.

With the rival American and European car industries competing to be the first to introduce electric vehicles to reduce dependence on oil, one German-based executive said these would begin to be commercially available in sizeable numbers from 2015. The real lift-off would come with the new carbon emissions targets from 2020.

Before the Irish vote against the Lisbon treaty provoked a constitutional headache, Brown proposed that this week's EU summit adopt an emissions target of 100 grams a kilometre by 2020, along with joint efforts to promote electric vehicles. Environmental campaigners want the 2020 target set lower at 80 grams.

The French president and German chancellor set a 2020 target of between 95 grams and 110 grams when they struck a deal in Bavaria last week to resolve a protracted dispute between the two countries over previous emissions goals.

The French and German leaders confirmed the average fleet limit for new cars should now be set at 120 grams from 2012 but agreed that it could be phased in over the three years to 2015 for certain heavier models.

In concessions to the German car industry, which produces heavier vehicles consuming more fuel, Sarkozy also agreed that "green" innovations such as solar panels on car roofs, seven-speed gear-boxes, improved tyres or hi-tech beams counted towards meeting the target.

Sarkozy and Merkel also agreed to sharply reduce the stiff penalties proposed by the European commission for missing the target amid industry warnings that these could cost billions of euros at their current levels.

Their breakthrough came after a more conciliatory approach towards the EU targets from the German car industry, whose main lobby group, the VDA, is now headed by a former government minister. An industry executive said: "It will now be far more constructive and moderate in its approach.

"You simply cannot lobby a mega-social and economic trend towards safer, less polluting cars away."