The right utility parameter – mass or footprint (or both)?

In 2009, the EU set legally-binding targets for new cars to emit 130 grams of CO₂ per kilometer (g/km) by 2015 and 95g/km in 2020.  In July, the Commission announced the outcome of its review of the modalities (ways) of achieving the 2020 target. The regulation takes account of the “utility” or purpose of the cars produced by different manufacturers whose targets therefore vary. In 2009, the EU agreed to account for the utility of the vehicles and set targets for individual manufacturers by comparing the average weight (mass) of the cars they produce. This was largely because data was not available on the average size (footprint) of registered cars until 2011. The Commission’s new proposal is to continue to use mass as a measure of utility until 2020 in order to minimize changes to the regulation.