## 3 Problem Analysis and Consequences of Potential Legislative Amendments for Calibration
### Increase of Possible Test Cases: \"Wider RDE Testing Range\"  
The extension of the defined boundary conditions in RDE testing is accompanied by an increase in the number of test cases required for calibration and validation. Adjusting or even eliminating the required minimum driving distances for a valid RDE test results is a significant challenge for calibration due to the high emission level during cold start and warm-up phase [53; 54]. Shortening the required total driving distance results in only a reduced distance to \"dilute\" the start emissions by the range covered in warm condition. For demonstration, the distance specific and cumulated PN, NO\({}_{\chi}\) and CO emissions for a WLTC test on a chassis dyno with a 1.6 1155 kW GDI 1783 kg D segment vehicle with a state-of-the-art exhaust aftertreatment system including a three-way catalytic converter and a GPF are shown in Figure 6. Due to the cold system conditions, the increased raw emissions, and the low conversion rate of the aftertreatment system lead to a high increase of cumulated emissions within the first 100 s. Once the catalytic converter has reached the light-off temperature, the conversion of the raw emissions reaches a suitable efficiency, leading to a clear reduction in tailpipe emissions. The distance specific intensity indicates the diluting effect of the following test distance on the overall result. Even a shorter distance after a cold-start with restricted driving dynamics [4] can significantly increase the emissions generated in this phase if higher loads and thus higher mass flows are provoked while the exhaust aftertreatment components have not yet reached the necessary operation and light-off temperatures. As a consequence, additional auxiliaries such as electrically or burner-heated exhaust aftertreatment systems must be applied to support the warm-up process [55; 56; 57; 2; 58]. Further measures such as the use of e-fuels for improved starting and emission behavior are conceivable to support an efficient calibration [59; 60; 61; 62]. The removal of limitations for driving dynamics (RPA and v-a\({}_{\text{pos95}}\)) as well as the topography of the route driven lead to a multitude of new engine operating conditions. In particular, the resulting dwell time in emission-critical engine operating points makes it difficult to robustly ensure emission compliance. Both the continuous operation in high load ranges and the operation at low load and low dynamics must be considered in the calibration [63]. Current concepts, which require enrichment for thermal component protection at high loads and exhaust gas temperatures, can no longer be used due to the expected combination of the elimination of driving dynamics limitations and additional emission restrictions (especially for CO). This will require a change to stoichiometric operation over the entire engine map [7; 30; 31]. Additionally, low loads in combination with changed driving route restrictions can lead to a slower warm-up of the components, especially during the urban phase as shown in [64]. Figure 6: Distance specific and cumulated emission results for PN, NO\({}_{\chi}\) and CO on a WLTC. Considering the increasing hybridization of current and future powertrains, the challenge of a wider range of potential operating points and operating point traces is further enhanced. This can result in hurdles and benefits at the same time. Being able to actively shift the operating point in load, speed and completely decouple it from the actual propulsion demand (based on the specific hybrid topology) allows optimizing the used operation area based on the emission behavior. At the same time, a compromise between emission optimization and reduction of fuel consumption needs to be addressed in the layout of the hybrid strategy calibration. This advantage of decoupling the engine may result with regard to temperature management of the engine and exhaust aftertreatment system. Repeated engine starts at temperatures with a low conversion efficiency may lead to an intensified emission behavior.