*Energies* **2020**, *13*, 2396



#### *Energies* **2020**, *13*, 2396

It is worth mentioning that 6.2% of the stamped and 54.7% of the forged steel parts; 95.8% of the casted and 100% of the forged iron parts; and, 91.4% of the casted and 3.4% of the extruded aluminum parts were also subjected to a machining process [19].

Secondly, the material flow of the material production processes was analyzed. Figure 3 was elaborated based on Sullivan et al. [19], GREET Excel Model Platform [21], Greet 2018 Net software [22], Ophardt [23], and Keoleian et al. [24], Brunham et al. [25]. The left side of the figure indicates the upstream of the productive supply chain (mining), where its output (raw material) is subjected to material productive processes before entering part production processes and it is finally assembled as a part of a vehicle in the assembly plant. This flow is quantified when considering both equations proposed above and through the following ones. The materials used to produce parts could be supplied by different material production processes, as indicated by Equation (3). Moreover, different quantities of raw materials are required to produce each material, as indicated by Equation (4).

$$\text{GMC}\_{\text{m,i}} = \sum\_{j} \text{GMP}\_{\text{m,j}\prime} \tag{3}$$

$$\text{GMC}\_{n,j} = \text{GMP}\_{m,j} \* \text{MC}\_{n,j\_\*} \tag{4}$$

where *GMPm*,*<sup>j</sup>* is mass of material m produced in productive process j, *GMCn*,*<sup>j</sup>* is mass of material n consumed in productive process j, and *MCn*,*<sup>j</sup>* is the mass of material n consumed in productive process j per mass material produced (process output), as shown in Table 1.

In the same way, the flow is extended upstream to cover all of the productive processes of the materials. Pressed steel parts are produced by hot rolling, cold rolling, and galvanized steel sheets. The first one represents 21.1%, the second one 19.1%, and the last one 59.8% of the final product mass [21]. Moreover, casted aluminum and iron parts, such as engine blocks, engine/exhaust components, and brake rotors, were used for its production recycled material. Here, it is considered that 85% of casted aluminum parts and the total of casted iron parts contain recycled materials.

Finally, the material flow of the vehicle-assembly phase was elaborated, when considering that the body of each vehicle is produced through the welding and painting of pressed steel parts. Subsequently, the rest of the supplied parts were added to it in the line, before a final verification of the entire vehicle to ensure its quality and functionality.

**Figure 3.** Production flow for a vehicle.
