§ 86.1821-01 Evaporative/refueling family determination.
(a) The gasoline-, ethanol-, metha-nol-, liquefied petroleum gas-, and natural gas-fueled vehicles described in a certification application will be divided into groupings expected to have similar evaporative and/or refueling emission characteristics (as applicable) throughout their useful life. Each group of vehicles with similar evaporative and/or refueling emission characteristics shall be defined as a separate evaporative/refueling family. Manufacturers shall use good engineering judgment to determine evaporative/refueling families. This section applies for all sizes and types of vehicles that are subject to evaporative or refueling standards, including those subject to standards under 40 CFR 1037.103.
(b) For vehicles that operate on volatile liquid fuels to be classed in the same evaporative/refueling family, they must be similar with respect to all the following items: