## 3 Problem Analysis and Consequences of Potential Legislative Amendments for Calibration
### Vehicle Testing according to Actual Use: \"Normal Use and Normal Conditions Will Be Reassessed\"  
The question arises how normal operation can be defined. An important aspect is the evaluation and quantification of operational and driving behavior with the respective vehicle.  
Within the RDE legislation, the key figures v-a\({}_{\text{pos95}}\) and RPA are implemented (Figure 3) [4]. However, these are not sufficient to clearly describe \"normal use\" [65]. The introduction of further indicators as described in [65; 66] is an important next step. The goal of focusing test procedures and operating modes on typical usage affects the calibration itself, the design of tests, and the evaluation and interpretation of test data. The demand for more realistic operating modes in legal tests has already been pursued by the introduction of the WLTC. To design this test cycle, statistical data of typical driving behavior was collected and the speed profile was derived from this data [67; 68]. More realistic tests cause more realistic emission results, e.g., compared to NEDC [69]. An equivalent approach was implemented in the Chinese emission legislation with the introduction of CATC [70]. With the goal of mapping geographically regional driving behavior in a more focused manner [71; 72; 73; 74], local target group-specific data are also collected, evaluated and, for example, combined into a supplementary test cycle via Markov chains (further explained in [75; 76; 77; 78]) as described in [79; 80].  
The shift away from predefined driving cycles to a focus on free RDE routes means however that the previously used approaches will also be revised in the future. Methods must be introduced that do not define statistically relevant driving profile sequences on the basis of databases, but rather determine statistical relevance by means of comparison algorithms. The EU6d standard does not specify any characteristic values that describe typical driving behavior. The driving dynamics-limiting parameters v-a\({}_{\text{pos95}}\) and RPA are only used to ensure comparable test requirements. The derivation of corresponding parameters and especially the determination of target values is highly relevant since the driving behavior influence the total emission results significantly [6; 81], but remains open.  
A definition of global statistical targets by the legislator remains difficult and impractical. Different vehicles and motorizations have correspondingly different statistically typical operating modes [82; 83; 84; 85]. With the goal of individual relevance, a target-oriented concept must leave the verification of the statistical relevance of a test drive to the manufacturer. In addition to the additional implementation of methods with statistical relevance, an increased calibration effort is necessary. Already in the case of derivative changes, the following changed typical usage behavior can lead to a shift in the focus of the calibration. Even with the same test, the emissions of a uniform propulsion system can vary in different vehicles, as shown in [82]. With the introduction of typical driving behaviors in the future, not only the effects of the vehicle on the operating point, but also the shifting of the operating points due to changed driving behavior will require extended calibration scopes.