In the NPRM, EPA and NHTSA relied on three studies to estimate the cost of vehicle mass

reduction. The NPRM used a value of $1.32 per pound of mass reduction that was derived from a 2002 National Academy of Sciences study, a 2008 Sierra Research report, and a 2008 MIT study. The cost was estimated to be constant, independent of the level of mass reduction. The agencies along with the California Air Resources Board (CARB) have recently completed work on an Interim Joint Technical Assessment Report (TAR) that considers light - duty GHG and fuel economy standards for model years 2017 through 2025 and have continued this work to support the light - duty vehicle NPRM , which is expected to be issued this fall . Based on new information from various industry and literature sources, the TAR report modified the mass reduction/cost relationship used in the 2012 - 2016 light - duty final rules to begin at the origin ( zero cost at 0% mass reduction) and to have increasing cost with increasing mass reduction. i The resulting an alysis showed costs for 5% mass reduction on light duty vehicles to be near zero or cost parity. In the proposal for heavy - duty vehicles, we estimated mass reduction costs based on the 2012 - 2016 light - duty analysis without accounting for the new work comp leted in the Interim Joint Technical Assessment and additional work the agencies have considered for the light - duty vehicle NPRM . Since the heavy - duty vehicle proposal, the agencies have been able to consider updated cost estimates in the context of both l ight - duty and heavy - duty vehicle bodies of work. While the agencies intend to discuss the additional work for the light - duty NPRM in much more detail in the documents for that rulemaking, we think it appropriate to explain here that after having considere d a number of additional and highly - varying sources, the agencies believe that the cost estimates used in the TAR may have been lower than would be reasonable for HD pickups and vans, given their different and work-related uses and thus different construction as compared to the light - duty vehicles evaluated in the TAR. W e do not believe that all of the weight reduction opportunities for light - duty vehicles can be applied to heavy - duty trucks. However, we do believe reductions in the following components and systems can be found that do not affect the payload and towing requirements of these heavy - duty vehicles; body, closure panels, glazing, seats and other interior components, engine cooling systems and HVAC systems. The agencies have reviewed and consi dered many different mass reduction studies during the technical assessment for the heavy - duty vehicle GHG and fuel efficiency rulemaking. The agencies found that many of the studies on this topic vary considerably in their rigor, transparency, and applic ability to the regulatory assessment. Having considered a variety of options, the agencies for this heavy - duty analysis have been unable to come up with a way to quantitatively evaluate the available studies. Therefore, the agencies have chosen a value within the range of the available studies that the agencies believe is reasonable. The studies and OEM confidential business information relied upon in determining the final mass reduction cost are summarized below in 

### Figure **Error! No text of specified style in document.**  Error! No text of specified s tyle in document. - 1 . Each study relied upon by the agencies in this determination has also been placed in the agencies’ respective dockets. See NHTSA2010 - 0079; EPA - HQ - 0AR - 2010 - 0162.**Figure** Error! No text of specified style in document. Error! No text of specified s tyle in document. **- 1**  **: Mass Reduction Cost Data Considered for Final Rulem**  **aking**

Thus, w e are estimating the direct manufacturing costs for a 5 percent mass reduction of a 6,000 lb vehicle at a range of $ 75 - $90 per vehicle . With additional margin for uncertainty, we arrive at a direct manufacturing cost of $85 - $100, which is roughly in the upper middle of the range of values that resulted from the additional and highly - varying studies mentioned above that were considered in the agencies’ review. We have broken this down for application to HD pickup trucks and vans as follows: Class 2b gasoline $85, Class 2b diesel $95, Class 3 gasoline $90, and Class 3 diesel $100 . Applying the low complexity ICM of 1.24 results in estimated total costs for a 5 percent mass reduction applicable in the 201 6 model year of: Class 2b gasoline $ 108 , Class 2b diesel $ 121 , Class 3 gasoline $ 115 , Class 3 diesel trucks $1 27. All mass reduction costs stated here are in 2009 dollars.

i “Interim Joint Technical Assessment Report: Light - Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards for Model Years 2017 - 2025 ;” September 2010; available at http://epa.gov/otaq/climate/regulations/ldv - ghg - tar.pdf and in the docket for this rule.