With regard to driving, it is not just the car itself and petrol consumption that are taken into account but also, proportionately, the iron ore mine, the steel mill and the road network, for example. Adding up all the raw materials gives a measure of the impact on the environment. This is because all material inputs and outputs cause changes in natural material flows and cycles. Sooner or later, every material input becomes an output again, i.e. waste or emissions. By recording the inputs, the MIPS concept developed at the Wuppertal Institute provides a rough estimate of the total environmental impact potential. MIPS stands for "material input per service unit".