According to German newspaper Handelsblatt, the amount of carbon dioxide a car can emit in the future could be determined by its weight.
Manufacturers producing cars that emit levels above this threshold will have to pay duties to those who fulfil the criteria or fall under them.
German conservative MEP Karl-Heinz Florenz told the paper the plans were the equivalent of an emissions trading system for cars.
Currently the EU applies a system to industry whereby firms are given pollution credits. Those using more than their allocated credits have to buy from firms that do not need all their credits.
The commission's plans for the car industry follow an announcement by Brussels in February that from 2012 all new cars should have an average limit of 130 grammes per kilometre of CO2 emissions.
Of this, 10 grammes in reduction would come through additional measures such as more efficient air conditioning and the use of biofuels.
At the moment, the average emissions of European cars is 160 g/km.