The use of cars for transportation is increasing, leading to more carbon dioxide emissions. If this trend continues, road transport could become the biggest source of CO2 emissions in the UK by 2020. This could make it harder to meet the government's goal of reducing emissions by 20% by 2010. Without action, emissions from road transport could keep rising after 2020, undoing progress made in other areas. It's important to act now to reduce CO2 emissions from road transport.