Abstract: In September 2011, the National Highway Traffic Safety Administration and U.S. Environmental Protection Agency promulgated the first-ever federal regulations mandating fuel economy improvements for heavy-duty commercial vehicles. While the performance-based approach to these rules offers familiarity and assurances of fuel economy improvements, it also has some well-known weaknesses. In this paper, we describe fuel economy technologies for the trucking sector, its economic structure, the details of the new fuel economy regulations, and the controversies they sparked. We then address issues raised in reviewing the accompanying regulatory impact analysis. Next, we highlight some flaws of this form of regulation and suggest a variety of alternative, more market-oriented approaches that might work better.