We kind of like this dyno as it calculated drivetrain loss as a multiplication instead of a set percentage. The outdated and erroneous thinking on the topic is that a car has a certain percentage of drivetrain loss which it does not as it depends on the RPM as well as gearing. You have to know what your loss is at what your peak HP is or else the numbers are completely arbitrary. We calculated the drivetrain loss here based on the drag HP as calculated by the dyno. What one calculates as drivetrain loss will vary dyno to dyno and RPM to RPM, something to remember as it is not uniform even though the components are static.
Factory crank numbers are calculated using SAE J 1349 so no matter what car you throw on the MAHA dyno it will readout to the manufacturer standard. In this case BMW underrated it just a bit. It will be interesting to see how this graph compares to the dynojet graphs we are used to in the USA due to the large sample size of dynojet graphs available to compare to. We hope this helps a bit in understanding how dyno's, drivetrain loss, crank, and wheel HP can all vary and it is important to understand the various factors involved before coming to a conclusion.
Here is an example graph that should help in reading MAHA dyno's in the future: