In spite of the important improvement in public transport achieved the last years, the private vehicle continues to represent a very large percentage in the commuting made in the city. This has consequent impacts on the quality of the air and on acoustic pollution.
In February 2006, Madrid City Council approved the Local Strategy of Air Quality 2006 - 2010, whose main important objective is the reduction of some air pollutants caused mainly by urban traffic. According to Local Strategy targets, NOx emissions should be decreased in the period between 2006-2010 to comply with European regulations. Particle matter and greenhouse gas levels have also been taken into consideration.
One of the measures of this strategy for achieving better air quality in Madrid city is to extend the use of biofuel, emphasising the use of clean vehicles within municipality fleet. Additionally, Madrid City is working on the Green Fleet Plan, which includes the promotion of the use of alternative fuels, as ethanol, biogas or biodiesel.