Study finds recent achieved CAFE performance outpacing levels projected to be achieved by NHTSA
3 October 2013
|Average monthly and model year fleet-wide achieved CAFE performance levels (light purple) versus NHTSA projected achieved CAFE levels (blue) for model years 2008 through 2016. Schoettle and Sivak 2013. Click to enlarge.|
Achieved Corporate Average Fuel Economy (CAFE) fuel economy performance has exceeded the anticipated levels for 2012 and 2013 model years—the two years that the current standard has been in effect—according to a new analysis by Michael Sivak and Brandon Schoettle at the University of Michigan Transportation Research Institute (UMTRI).
Additionally, they found, achieved CAFE performance has consistently increased annually from model year 2008 through model year 2013. If the current trends in annual improvements continue, future CAFE performance is expected to continue meeting or exceeding the projected performance levels (and desired greenhouse gas reductions) contained in the latest CAFE standards.
In August 2012, the US Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) announced the final standard governing new-vehicle fuel economy for model years 2017 through 2025. (Earlier post.)
NHTSA developed two phases of standards in this rulemaking. The first phase, from MYs 2017-2021, includes final standards that are projected to require, on an average industry fleet-wide basis, a range from 40.3—41.0 mpg US (5.84 to 5.74 L/100km) in MY 2021. The second phase of the CAFE program, from MYs 2022-2025, includes standards that are not final, due to the statutory requirement that NHTSA set average fuel economy standards not more than 5 model years at a time. NHTSA projects that those standards could require, on an average industry fleet wide basis, a range from 48.7–49.7 mpg (4.83 to 4.73 L/100km) in model year 2025.
|Average fleet-wide CAFE performance targets and the corresponding projected achieved performance levels (without credits) for model years 2012 through 2025. Schoettle and Sivak 2013, EPA/NHTSA 2010, 2012). Click to enlarge.|
EPA established standards that are projected to require, on an average industry fleet-wide basis, 163 grams/mile of carbon dioxide in model year 2025, which would be equivalent to 54.5 mpg (4.3 L/100km) if this level were achieved solely through improvements in fuel efficiency. However, the agencies expect that a portion of these improvements will be made through improvements in air conditioning leakage and through use of alternative refrigerants, which would not contribute to fuel economy, as well as the use of alternative credits.
NHTSA refers to anticipated actual performance (without credits) as “projected achieved”. (See chart at right.)
Sivak and Schoettle compared the recent improvements in fuel economy with the projected CAFE performance levels anticipated by NHTSA. Sales-weighted, unadjusted CAFE performance was calculated from the monthly and annual sales of individual models of light-duty vehicles and the unadjusted combined city/highway fuel-economy ratings for the respective models. (Unadjusted figures are higher than the “window-sticker” adjusted ratings on new car labels.)
Sivak and Schoettle did not factor in the various credits and adjustments available to manufacturers when determining final CAFE performance values. Hence, the calculations in this report represent the actual achieved CAFE performance for the new vehicle fleet. The UMTRI team compared the results with the projected achieved fleet-wide CAFE performance published by NHTSA.
Overall, they found that the two most recent model years (2012 and 2013) experienced an increase of 1.0 mpg and 0.9 mpg, respectively, in average fleet-wide achieved CAFE performance. Overall, achieved CAFE performance has improved by 4.3 mpg from model years 2008 to 2013 from 25.5 mpg (9.22 l/100 km) to 29.8 mpg (7.89 l/100 km)—a 16.9% improvement.
For the two model years completed under the current standard (2012 and 2013), the achieved performance levels exceeded NHTS’a anticipated levels by 0.2 mpg and 0.1 mpg, respectively.
Brandon Schoettle and Michael Sivak (2013) A Comparison of CAFE Standards and Actual CAFE Performance of New Light-Duty Vehicles (UMTRI-2013-35)
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