Each time NHTSA proposes or finalizes new CAFE standards, the agency must consider options and estimate the impacts of each option.  For all CAFE rulemakings since 2003, NHTSA has made significant use of results produced by the CAFE Compliance and Effects Model (commonly referred to as “the CAFE model” or “the Volpe model”), developed by DOT’s Volpe National Transportation Systems Center to support NHTSA’s CAFE rulemakings. NHTSA uses the model as a tool to estimate how manufacturers could attempt to comply with a given CAFE standard by adding technology to anticipated future vehicle fleets, and to estimate impacts of that additional technology on fuel consumption, greenhouse gas emissions, and economic costs and benefits to vehicle owners and society.  NHTSA also uses the model to evaluate the sensitivity of these estimated outcomes to key analytical inputs (e.g., fuel prices), and to perform probabilistic uncertainty analysis.

• Watch: Video introduction to the CAFE Model (updated Sept. 24, 2018, to included captioning)

Available Versions and Analyses

NHTSA has continually improved the CAFE model, and with every new CAFE rulemaking since 2008, NHTSA releases the version used, its source code, and the inputs and outputs that underlay the rulemaking analysis. The following are major ways the model has evolved over time.

• 2015: More explicit representation of shared vehicle platforms and engines; modifications to analyze options for future fuel consumption standards for heavy-duty pickup trucks and vans (e.g., Ford F-350 pickup trucks and Mercedes Sprinter vans).
• 2016 (Draft TAR version): Improvements to model’s approach to calculating fuel consumption impacts of different technologies; adds option for simultaneous analysis of light-duty CAFE standards and heavy-duty pickup and van fuel consumption standards, accounting for some of the interactions between these market segments.  
• 2018 (MYs 2021-2026 NPRM version): Adds ability to simulate compliance with CO2 standards as well as CAFE standards; adds sales and scrappage modules.  
• 2020: (MYs 2021-2026 final rule version) Refinements to sales and scrappage modules; adds accounting methods to apply factors used to estimate extent to which changes in quantities of emissions (e.g., ozone precursors) could lead to various types of health impacts (e.g., hospital admissions for asthma attacks).

Outlook

NHTSA and the Volpe Center are continuing to develop the model to support future fuel-economy-related analyses. New versions of the model will be released along with future NHTSA analyses.

Contact:  Kevin Green (Kevin.Green@dot.gov)

The model, its system documentation, source code, and input files can be downloaded from NHTSA's ftp server via the links below (listed from newest to oldest).  Many of these archives were compressed using 7-zip, which is available at www.7-zip.org.