1. Evaluation on Maximum CO2-Delta in 2-Tests-Approach
WLTP-DTP-LabProcICE-238
Evaluation on Maximum CO2-Delta in 2-Tests-Approach
Simulation example with wide spread family data
A. Feucht Audi AG

2. Comparison of simulation values against interpolation with 2-test-approach
Family of A4 sedan (bc), A4 hatchback, A5 Coupe, A5 Cabrio, A4 allroad (wc)
Same 4-cyl. gasoline engine and 7-gear-aut. transmission, 4WD, same n/v-ratio
TML: 1674kg; TMH 1948 kg
Difference in cd*A: m2
Rolling resistance: min: 6,5 kg/t; max: 10,5 kg/t
Weight RR
Aero
⊿CO2 total =32.8g ① ③ ② ④ ⑧ ⑤ ⑦ ⑥
Worst
Best 9
Annette Feucht, I/EG-341, _max_Delta_2-tests-approach, 21. Mai 2013

3. Results
Overall deviation between the simulation test and the interpolated values is less than 0.7 g/km for the standard gasoline engine with an interpolation range of 32.8 g/km
Intermediate range „individual“ vehicle, which is most likely to be configured by the customer, shows even less deviation in all phases.
Annette Feucht, I/EG-341, _max_Delta_2-tests-approach, 21. Mai 2013

4. Conclusion
Interpolation between measured best- and worst-case-vehicle regarding to rolling resistance coefficient, aerodynamic drag and weight is at least as accurate as measuring more configurations for interpolation.
This is because in a CO2-measurement of an individual set of parameters the tolerances and measurement insecurities add up (RLD + dyno setting + WLTP measurement) and with a reasonable number of measurements the overall-tolerance is at least 1 g/km rather 2-3 g/km (0,1 l/100km).
It is demonstrated that the 2-test-interpolation method also works for best-case to worst-case differences of over 30g/km if only mass, rolling resistance and aerodynamics are changed in a car.
Annette Feucht, I/EG-341, _max_Delta_2-tests-approach, 21. Mai 2013