With the beginning of 2015, some new rules for cars emissions will come forwards in Europe: vehicles will have not to emit more than an average of 130 grams of CO₂ per kilometer and, by 2021, the target will be further reduced at 95 grams. In fact, road transport contributes to about one-fifth of the European's total emissions of carbon dioxide, the main greenhouse gas. And transport is the only major sector in the Europe where greenhouse gas emissions are still rising. Europe is still far from achieving its objectives about levels of air quality, in order to reduce