Bren Students Contribute to New CAFE Standards

May 3, 2010

Bren Students Have Impact on New Federal Rules for Vehicle Fuel Mileage and Emissions

Graduate school is often thought of as a place where students acquire knowledge and skills that will enable them to make an impact in the real world after they graduate. But a group of students at UC Santa Barbara's Bren School of Environmental Science & Management have put their stamp on a new federal regulatory rule before leaving the sometimes insular world of academia.

The result is that anyone who ever digs in to the Federal Register to read about a rule established on April 1, 2010 to control greenhouse gas emissions and increase corporate average fuel economy (CAFE) will find more than a dozen permanent mentions of Bren master’s and PhD students. The rule was drafted by the U.S. Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) at the request of the Obama administration. Among the many references to the students is an acknowledgement of their suggestions, offered during the public-comment period, that led to the discovery of some errors in data used to develop the rule.

The students engaged with the rule-making process as a project for an advanced seminar in regulatory analysis taught by Bren professor Charles Kolstad during fall quarter, 2009.

“The proposed new rule was an opportunity for Bren students and faculty to actually influence public policy, and the students rose to the occasion in such an impressive way,” says Kolstad. “They took a leadership role in analyzing the proposed regulation and also took the initiative to ‘look under the hood.’ The fact that the federal government seems to have paid so much attention to their work is a testament to the hands-on nature of a Bren education.”

The ten-member student group—PhD students Mary Collins, Zack Donohew, Natalija Glusac (all from Bren), and Liz Witham (Economics); and Bren master’s students LeeAnne French, Laura Hamman, Takuma Ono, Alexandra Speers, Katie Tannenbaum, and Robin Vercruse—analyzed and critiqued the proposed rule, submitted findings during the public-comment period, and had one member give an oral presentation at a public-comment event in Los Angeles.

“This was a unique opportunity for Bren students to apply their technical knowledge to a real problem and participate in the political process,” says Bren assistant professor Sarah Anderson, a political scientist who collaborated with Kolstad and the students. “And that process is where science and technical knowledge developed at schools like Bren find their way into policy that affects the nation as a whole.”

“It was a great learning experience, and we were gratified to see that what we said seemed to matter,” says Alexandra Speers, who spoke for the group at the public-comment session in L.A. “Bren really prepared us well for this. In every class, we’re taught how to collaborate with other students and professors. All the people in our group came from different backgrounds and had different interests, but we worked really well together. Everyone was passionate about wanting to make good comments about the rule and ensure that it was well thought out and well planned because it’s setting a precedent for greenhouse gas regulations.”

From the perspective of PhD student Natalija Glusac, the project served to reconnect her with the day-to-day applications of science. “In the PhD world, you can get myopic about your work,” she says. “It’s good to pull back and realize that you’re generating information and that if you present it effectively, people can use it.”

At one point in their project, the students spent hours using a variety of statistical tools to re-create a curve in the proposed rule, expressing the relationship between vehicle footprint (in square feet) and fuel economy, expressed in gallons per mile. But despite using all the statistical tools at their disposal, they could neither reproduce the curve nor discover how the regulators had produced it.

Their written report therefore included the following passage:

“…we recommend that the method with which the curves were drawn be made transparent in the support documentation…. We attempted to use the VOLPE model output data from NHTSA's website to reproduce the footprint curve, in order to assess the method with which the curve was drawn…. However, we were unable to reproduce the maximum technology curve and, therefore, could not compare the MAD methodology to alternative regressions.

“…We were unable to clarify these questions and replicate the exact slope and intercept given in the VOLPE model output…. This is a crucial piece of information, as the curve is the central tool with which the fuel economy targets are assigned.”

The students’ comments about the lack of transparency regarding the methods used to develop the curves, which were, in turn, used to create the rule, were echoed by other groups, including the Environmental Defense Fund. After reviewing the comments and retracing the methodology and looking again at how it was used to develop the curves, the EPA and NHTSA discovered a number of errors in their data. Their finding led to an acknowledgement of the students in the final version of the rule, which reads:

“Finally, considering comments by the UC Santa Barbara students regarding difficulties reproducing NHTSA’s analysis, NHTSA reexamined its analysis, and discovered some erroneous entries in model inputs underlying the analysis used to develop the curves…. These errors are discussed in NHTSA’s final Regulatory Impact Analysis (FRIA) and have since been corrected…. These errors, while not significant enough to impact the overall analysis of stringency, did affect the fitted slope for the passenger car curve and would have prevented precise replication of NHTSA’s NPRM analysis by outside parties.”

“The point of our project was not to fact-check the data, but to ensure that we understood the methodology well enough so that we could be certain if we came up with a curve that was more appropriate,” Glusac explains. “The data seemed to go into a ‘black hole, and it was difficult, if not impossible, to get, especially in the short time we had to find it. Even professional researchers who work on this kind of thing all the time couldn’t locate it.”

The group’s report included comments on seven aspects of the proposed rule:

  • the social cost of carbon

  • the stringency of targets

  • credits for electric vehicles

  • standards for non-CO2 greenhouse gases

  • mobile air-conditioning units

  • current emissions-testing protocols

  • car/light-truck vehicle classification


The new rule governing GHG emissions and fuel-economy standards was developed by the EPA and NHTSA in response to a directive from the Obama administration, which wants to regulate carbon emissions as part of an effort to mitigate global climate change.

See the report from the Bren seminar working group at:

See the complete “Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards Final Rule at: