The weight of a vehicle is directly correlated to fuel consumption and CO2 emission.
Modern vehicles have increased application of plastics, which are lighter than steel, especially for the non-stressed parts.
In the future we will see that more plastic will be used within the design of a vehicle and material such as magnesium and aluminum will be more and more applied for seat frames, etc.
The material that will replace the steel in a vehicle body needs to be strong. Advanced lightweight materials that will belong to the future vehicle could be HSLA (High Strength Low Alloy), aluminum, magnesium, fiber-reinforced and other composites, or kevlar for example.
Potential fuel economy benefit – [10-20%]
More on vehicle weight.