having to test each vehicle. In effect the regulatory effort has cascaded down to the component manufacturer, providing much-needed design flexibility to the final-stage manufacturer (which would not have to test every vehicle design variation). Aspects of this regulatory model may prove useful in the development of regulatory instruments for governing heavy-duty truck fuel consumption.


Finding 3-1. Regulators have dealt effectively with the diversity and complexity of the vehicle industry for current laws on fuel consumption and emissions for light-duty vehicles. Engine-based certification procedures have been applied to address emissions from heavy-duty vehicles and the myriad of nontransportation engines. Regulators and industry have reached consensus in these cases, but years of development of procedures and equipment for certification, compliance, and the defining the standards themselves have been required. Standardized drive or operating cycles are utilized in all emissions and fuel consumption regulations to represent actual use of the vehicle or engine.

Finding 3-2. The heavy-duty-truck fuel consumption regulations in Japan, and those under consideration and study by the European Commission (EC), provide valuable input and experience to the U.S. plans. In Japan the complexity of medium- and heavy-duty vehicle configurations and duty cycles was determined to lend itself to the use of computer simulation as a cost-effective means to calculate fuel efficiency. The EC studies thus far indicate plans to develop and use simulations in the expected European regulatory system. Japan is not using extensive full-vehicle testing in the certification process, despite the fact that its heavy-duty-vehicle manufacturing diversity is less than in the United States, with relatively few heavy-duty-vehicle manufacturers and no independent engine companies.

Finding 3-3. The existing regulations pertaining to medium- and heavy-duty vehicle safety and emissions provide examples indicating that the industry’s diversity is addressed by requiring compliance, or at least conformity, at the component level, reducing the regulatory burden on the final-stage manufacturer and thus preserving the flexibility of assembly to meet customer demands.

Finding 3-4. The legislation passed by California requiring tractor-trailer combinations to be SmartWay certified will have a significant impact on the number of vehicles in the United States that are specified with fuel-efficient technologies beginning in 2010.


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