Measuring and modeling of rolling resistance

Limited resources and the higher awareness of the influence of CO2 emissions on global warming have led to stricter legal regulations. The aim of 20 % cut in CO2-emissions until 2020 compared to levels of 1990 was declared by the European Union [1]. Transportation has a share of 26 % on these emissions. Therefore different regulations including fleet consumption levels for passenger car manufacturers have been introduced and increase the pressure to develop more efficient cars.Besides the development of more efficient or ideally CO2 neutral drivetrains (which are only possible for 100 % regenerative generation of power), the reduction of driving resistances is one of the main instruments to achieve this objective. The external driving resistances consist of Air resistanceRolling resistanceAcceleration resistanceClimbing resistance Rolling resistance, acceleration and climbing resistance depend on the mass of the vehicle. However, increased safety and comfort requirements together with production costs specifications limit the opportunities for more efficient cars due to mass reduction. On electrical powered vehicles, kinetic and potential energy can be regenerated to a large extend. Therefore acceleration and climbing resistance can be compensated partly and air drag and rolling resistance are more important than for conventionally powered vehicles. Furthermore, electrical powered vehicles are often used in urban surroundings at relatively low speeds, at which rolling resistance becomes the dominant driving resistance.