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.
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. Here's a look at major ways the model has evolved over time.
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.
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).
2023 NPRM for Model Years 2027-2032 Passenger Cars and Light Trucks and Model Years 2030-2035 Heavy-Duty Pickup Trucks and Vans
2022 Final Rule for Model Years 2024-2026 Passenger Cars and Light Trucks
2021 Proposed Rule for Model Years 2024-2026 Passenger Cars and Light Trucks
2020 Final Rule for Model Years 2021-2026 Passenger Cars and Light Trucks
2018 NPRM for Model Years 2021-2026 Passenger Cars and Light Trucks
- Model Software
- Model Source Code
- Model Documentation
- Central Analysis
- MY Standard Attribution for CAFE
- MY Standard Attribution for CO2
- Sensitivity Analysis
- Supplementary R scripts for table calculations
- CAFE Model Peer Review
- Assessment of CAFE Model Vehicle Sales, Scrappage, and Labor Utilization used for SAFE NPRM (07/03/2019)
2016 Final Rule for Model Years 2021-2027 Heavy-Duty Pickups and Vans
2016 Draft TAR for Model Years 2022-2025 Passenger Cars and Light Trucks
2015 NPRM for Model Years 2021-2027 Heavy-Duty Pickups and Vans
2012 Final Rule for Model Years 2017-2021 Passenger Cars and Light Trucks
- System Documentation
- Model Software
- Source Code
- Calibration of Curves For the Final Rule, the coefficients used for the CAFE standard were not recalibrated. For reference, the final step of curve-calibration performed during the NPRM is included.
- Uncertainty Analysis
- Evaluation of Alternatives
- EIS Analysis
- Input Sheet File Descriptions
- 2017+ Expanded Decision Tree 2010 Baseline
- 2017+ Final CAFE Model Input File 2010 Baseline
- 2017+ Technology Cost Data File 2010 Baseline