40 CFR § 86.000-24 - Test vehicles and engines.
(b) introductory text [Reserved]
(i) Vehicles are chosen to be operated and tested for emission data based upon engine family groupings. Within each engine family, one test vehicle is selected. If air conditioning is projected to be available on any vehicles within the engine family, the Administrator will limit selections to engine codes which have air conditioning available and will require that any vehicle selected under this section has air conditioning installed and operational. The Administrator selects as the test vehicle the vehicle with the heaviest equivalent test weight (including options) within the family which meets the air conditioning eligibility requirement discussed earlier in this section. If more than one vehicle meets this criterion, then within that vehicle grouping, the Administrator selects, in the order listed, the highest road-load power, largest displacement, the transmission with the highest numerical final gear ratio (including overdrive), the highest numerical axle ratio offered in that engine family, and the maximum fuel flow calibration.
(ii) The Administrator selects one additional test vehicle from within each engine family. The additional vehicle selected is the vehicle expected to exhibit the highest emissions of those vehicles remaining in the engine family. The selected vehicle will include an air conditioning engine code unless the Administrator chooses a worst vehicle configuration that is not available with air conditioning. If all vehicles within the engine family are similar, the Administrator may waive the requirements of this paragraph.
(3) Except for air conditioning, where it is expected that 33 percent or less of a carline, within an engine-system combination, will be equipped with an item (whether that item is standard equipment or an option) that can reasonably be expected to influence emissions, that item may not be installed on any emission data vehicle or durability data vehicle of that carline within that engine-system combination, unless that item is standard equipment on that vehicle or specifically required by the Administrator.
(4) Air conditioning must be installed and operational on any emission data vehicle of any vehicle configuration that is projected to be available with air conditioning regardless of the rate of installation of air conditioning within the carline. Section 86.096-24(g) (1) and (2) and paragraph (g)(3) of this section will be used to determine whether the weight of the air conditioner will be included in equivalent test weight calculations for emission testing.