Selective enforcement audit provisions apply for axles and transmissions relative to the efficiency demonstrations of §§1037.560 and 1037.565 as follows:

(a) A selective enforcement audit for axles or transmissions would consist of performing measurements with a production axle or transmission to determine mean power loss values as declared for GEM simulations, and running GEM over one or more applicable duty cycles based on those measured values. The engine is considered passing for a given configuration if the new modeled emission result for every applicable duty cycle is at or below the modeled emission result corresponding to the declared GEM inputs.

(b) Run GEM for each applicable vehicle configuration identified in 40 CFR 1036.540. For axle testing, this may require omitting several vehicle configurations based on selecting axle ratios that correspond to the tested axle. The GEM result for each vehicle configuration counts as a separate test for determining whether the family passes or fails the audit. Select additional production axles or transmissions to perform additional tests as needed.