This SAE Recommended Practice establishes uniform chassis dynamometer test procedures for hybrid-electric vehicles (HEVs) that are designed to be driven on public roads. The procedure provides instructions for measuring and calculating the exhaust emissions and fuel economy of HEV's driven on the Urban Dynamometer Driving Schedule (UDDS) and the Highway Fuel Economy Driving Schedule (HFEDS), as well as the exhaust emissions of HEVs driven on the US06 Driving Schedule (US06) and the SC03 Driving Schedule (SC03). However, the procedures are structured so that other driving schedules may be substituted, provided that the corresponding preparatory procedures, test lengths, and weighting factors are modified accordingly. Furthermore, this document does not specify which emissions constituents to measure (e.g., HC, CO, NOx, CO2); instead, that decision will depend on the objectives of the tester.
For purposes of this test procedure, an HEV is defined as a road vehicle that can draw propulsion energy from both of the following sources of stored energy: 1) a consumable fuel and 2) a rechargeable energy storage system (RESS) that is recharged by an electric motor-generator system, an off-vehicle electric energy source, or both. Consumable fuels that are covered by this document are limited to petroleum-based liquid fuels (e.g., gasoline and Diesel fuel), alcohol-based liquid fuels (e.g., methanol and ethanol), and hydrocarbon-based gaseous fuels (e.g., compressed natural gas). RESS’s that are covered by this document include batteries, capacitors, and electromechanical flywheels. Single-roll, electric dynamometer test procedures are specified to minimize the test-to-test variations inherent in track testing and to conform with standard industry practice for exhaust emissions and fuel economy measurements. Also, this document does not include test procedures for "recharge-dependent" operating modes (see 3.1.12 for definition).