p-km/v-km).Р3.2. Improving fuel efficiencyР Improving the energy efficiency of cars is often seen as a means of addressing not only greenhouse gas emissions, but also air pollution and global oil depletion/supply security. Two general approaches are possible.Р The first is to decrease the road load – the sum of rolling, inertial, and air resistance – a general approach that will be needed by all future vehicles, whether private or public transport. Reducing the mass of the vehicle by using lighter weight materials is the most important means of decreasing the road load. The second is to improve the share of input energy that drives the wheels. Electric drive is today regarded as the best approach for achieving this aim, mainly because it enables regenerative braking and eliminates idling.