1. WLTP Annex 4 and 7, delta cd*A
WLTP-08-21e
BMW,
Christoph Lueginger
WLTP Annex 4 and 7, delta cd*A
Alternative determination methods

2. WLTP Annex 4 and 7, Delta cd*Af Alternatives for cd*AF determination
Proposal:
Allow also for other determination methods for similar options (e.g. by simulation) under agreement of type approval authority while keeping measurements as the basis.
Justification:
The difference between very similar options (e.g. same rim on different bodystyles) may be smaller than the measurement tolerance of cd*Af. In this case we could reduce unnecessary effort (wind tunnel measurements are very costly and time consuming) by using other tools that give the same accuracy.
The measurement should remain the basic principle!
At the request of the manufacturer and with the agreement of the type approval authority an equivalent method (e.g. simulation) can be used for the determination of a defined and limited number of options.
WLTP micro proposals, BMW,