Subject: Preamble II.G Safety for Interagency Review From: [james.tamm@dot.gov]

Sent: 11/12/2011 02:00 PM EST To: <Chandana_L._Achanta@omb.eop.gov> Cc: <rebecca.yoon@dot.gov>; William Charmley

Hi Chandana,

Attached is draft revised text for the Preamble II. G Safety Considerations in Establishing CAFE/GHG
Standards. The section includes revised text to ad dress the November 10, 2011 interagency comment #3 ( begins in the last paragraph on page 30), and text that more fully describes the agencies’ consideration of safety in selecting mass reduction levels (begins in the last paragraph on page 28).

For reference, below is November 10, 2011 Interagen cy Comment #3. Interagency Comment 3) Effect of rule on the distribution of the fleet fo otprint . Interagency commenters recommend that EPA and RIA include the f ollowing description in the Preamble discussion of safety impacts: “The standards in this proposal are intended to eli minate to comply by changing the size (i.e., footpr int) of vehicles. This is a well-understood problem with prior “flat” standards, which the National Academy of Sciences concluded [2002 report] led to adverse safety consequences, among other effects. Nevertheless the agencies acknowledge it is possibl e that changing the footprint could, under certain circumstances, be a relatively low-co st means of achieving compliance with the standards proposed today. This could happen in one of two way s. Manufacturers could change the size of a vehicle during the redesign cycle in order to increase over all fuel economy relative to the target for that particular vehicle size. (Footnote: Suppose, for ex ample, a 50-square-foot vehicle would exceed its target by 2 mpg, but a redesigned new vehicle would cost the same but exceed the slightly larger targe t by 3 mpg.) Alternatively, instead of redesigning ve hicles, manufacturers could lower the price and increase production of vehicles of sizes whose fuel economy is favorable (well above the target for th at footprint) and/or increase the price and decrease p roduction those whose fuel economy is unfavorable. For example, the agencies note that the standard is flat for vehicles smaller than roughly 41 square f eet. Further downsizing in this category could be a rela tively low-cost way of helping achieve overall compliance. To the extent manufacturers engage in e ither behavior, the net result would be vehicles larger or smaller on average than they otherwise wo uld have been in the absence of this regulation. Changes to the average size, and/ or the distributi on of vehicle sizes, could also have important implications for the overall safety of the new vehi cle fleet. For various reasons, the analysis assumes this rule will not have either of the effects described abov e. In other words, it will have no effect on the sales-we ighted distribution of vehicle footprints. In parti cular, the analysis assumes production of vehicles with fo otprints where the curve is flat (i.e., below 41 sq uare feet) will not increase over their baseline levels (i.e., those that will exist in MY 2016) as a resul t of this rule. We seek comment on the appropriateness of the overall assumptions that this rule will have no effect on the overall sales-weighted distribution o f vehicle footprints of on the sales of vehicles sm aller than 41 sq ft. Please provide data and/or other evi dence to support any claim general or specific that
the size distribution of the fleet will or will not change as a result of this rule.”

JimJames Tamm

Fuel Economy Division Chief Office of Rulemaking National Highway Traffic Safety Administration
Rm W45-340 1200 New Jersey Ave. SE Washington, DC 20590

II.G Safety Considerations to OMB 11-12-11.docx*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 1 of 32 G. Safety Considerations in Establishing CAFE/GHG Stan dards

1. Why do the agencies consider safety?

The primary goals of the proposed CAFE and GHG stan dards are to reduce fuel consumption and GHG emissions from the on-road ligh t-duty vehicle fleet, but in addition to these intended effects, the agencies also consider the potential of the standards to affect vehicle safety. 1 As a safety agency, NHTSA has long considered the potential for adverse safety consequences when establishing CAFE standards, 2 and under the CAA, EPA considers factors related to public health and human welfare, and saf ety, in regulating emissions of air pollutants
from mobile sources. 3 Safety trade-offs associated with fuel economy in creases have occurred in the past (particularly before NHTSA CAFE standards were attribute-based), and the agencies must be mindful of the possibility of future ones. These past safety trade-offs may have occurred because manufacturers chose, at the time, to build smaller and lighter vehicles—partly in response to CAFE standards—rather than adding more expensive fuel-saving technologies (and maintaining vehicle size and safety), and the small er and lighter vehicles did not fare as well in crashes as larger and heavier vehicles. Historical ly, as shown in FARS data analyzed by NHTSA, the safest cars generally have been heavy an d large, while the cars with the highest fatal-crash rates have been light and small. The qu estion, then, is whether past is necessarily prologue when it comes to potential changes in vehi cle size (both footprint and “overhang”) and mass in response to these proposed future CAFE and GHG standards. Manufacturers have stated that they will reduce vehicle mass as one of the co st-effective means of increasing fuel economy and reducing CO 2 emissions in order to meet the proposed standards, and the agencies have incorporated this expectation into our modeling ana lysis supporting the proposed standards. Because the agencies discern a historical relations hip between vehicle mass, size, and safety, it is reasonable to assume that these relationships will continue in the future. The question of whether vehicle design can mitigate the adverse eff ects of mass reduction is discussed below.

Manufacturers are less likely than they were in the past to reduce vehicle footprint in order to reduce mass for increased fuel economy. T he primary mechanism in this rulemaking for mitigating the potential negative effects on safety is the application of footprint-based standards, which create a disincentive for manufacturers to pr oduce smaller-footprint vehicles. See section II. C.1, above. This is because, as footprint decr eases, the corresponding fuel economy/GHG

1 In this rulemaking document, “vehicle safety” is d efined as societal fatality rates per vehicle miles traveled (VMT), which include fatalities to occupants of all the ve hicles involved in the collisions, plus any pedestr ians.

2 This practice is recognized approvingly in case la w. As the United States Court of Appeals for the D .C. Circuit stated in upholding NHTSA’s exercise of judgment in setting the 1987-1989 passenger car standards, “NH TSA has always examined the safety consequences of the CAFE standards in its overall consideration of relevant factors since its earliest rulemaking under the CAFE progra m.” Competitive Enterprise Institute v. NHTSA (“CEI I”) , 901 F.2d 107, 120 at n. 11 (D.C. Cir. 1990).

3 See NRDC v. EPA, 655 F. 2d 318, 332 n. 31 (D.C. C ir. 1981).(EPA may consider safety in developing st andards under section 202 (a) and did so appropriately in t he given instance).*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 2 of 32 emission target becomes more stringent. We also be lieve that the shape of the footprint curves themselves is approximately “footprint-neutral,” th at is, that it should neither encourage manufacturers to increase the footprint of their fl eets, nor to decrease it. Upsizing footprint is also discouraged through the curve “cut-off” at lar ger footprints. 4 However, the footprint-based standards do not discourage downsizing the portions of a vehicle in front of the front axle and to the rear of the rear axle, or of other areas of the vehicle outside the wheels. The crush space provided by those portions of a vehicle can make im portant contributions to managing crash energy. Additionally, simply because footprint-bas ed standards create no incentive to downsize
vehicles does not mean that manufacturers will not downsize if doing so makes it easier to meet the overall CAFE/GHG standard, as for example if th e smaller vehicles are so much lighter that they exceed their targets by much greater amounts. On balance, however, we believe the target curves and the incentives they provide generally wi ll not encourage down-sizing (or up-sizing) in terms of footprint reductions (or increases). 5

Given that we expect manufacturers to reduce vehicl e mass in response to the proposed standards, and do not expect manufacturers to reduc e vehicle footprint in response to the proposed standards, the agencies must attempt to pr edict the safety effects, if any, of the proposed standards based on the best information cu rrently available. This section explained why the agencies consider safety; the following sec tion discusses how the agencies consider safety.

2. How do the agencies consider safety?

Assessing the effects of vehicle mass reduction and size on societal safety is a complex issue. One part of estimating potential safety eff ects involves trying to understand better the relationship between mass and vehicle design. The extent of mass reduction that manufacturers may be considering to meet more stringent fuel econ omy and GHG standards may raise different safety concerns from what the industry has previous ly faced. The principal difference between the heavier vehicles, especially truck-based LTVs, and the lighter vehicles, especially passenger cars, is that mass reduction has a different effect in collisions with another car or LTV. When

4 The agencies recognize that at the other end of th e curve, manufacturers who make small cars and truc ks below 41 square feet (the small footprint cut-off point) hav e some incentive to downsize their vehicles to make it easier to meet the constant target. That cut-off may also cr eate some incentive for manufacturers who do not cu rrently offer models that size to do so in the future. However, at the same time, the agencies believe that there i s a limit to the market for cars and trucks smaller than 41 square f eet: most consumers likely have some minimum expec tation about interior volume, for example, among other thi ngs. Additionally, vehicles in this segment are th e lowest price point for the light-duty automotive market, with se veral models in the $10,000-$15,000 range. Manufac turers who find themselves incentivized by the cut-off will al so find themselves adding technology to the lowest price segment vehicles, which could make it challenging to retain the price advantage. Because of these two reasons , the agencies believe that the incentive to increase the sales of vehicles smaller than 41 square feet due to this r ulemaking, if any, is small. See Section II.C.1 above and Chapter 1 of the draft Jo int TSD for more information on the agencies’ choice of “cut-off” points for the footprint-based target curves.
5 This statement makes no prediction of how consumer choices of vehicle size will change in the future, independent of this proposal.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 3 of 32 two vehicles of unequal mass collide, the change in velocity (delta V) is higher in the lighter vehicle, similar to the mass ratio proportion. As a result of the higher change in velocity, the fatality risk may also increase. Removing more mas s from the heavier vehicle than in the lighter vehicle by amounts that bring the mass ratio closer to 1.0 reduces the delta V in the lighter vehicle, possibly resulting in a net societal benef it.

Another complexity is that if a vehicle is made lig hter, adjustments must be made to the
vehicle’s structure such that it will be able to ma nage the energy in a crash while limiting intrusion into the occupant compartment after adopt ing materials that may be stiffer. To maintain an acceptable occupant compartment deceleration, th e effective front end stiffness has to be managed such that the crash pulse does not increase as stiffer yet lighter materials are utilized. If the energy is not well managed, the occupants may h ave to “ride down” a more severe crash pulse, putting more burdens on the restraint system s to protect the occupants. There may be technological and physical limitations to how much the restraint system may mitigate these
effects.

The agencies must attempt to estimate now, based on the best information currently available to us, how the assumed levels of mass red uction without additional changes (i.e. footprint, performance, functionality) might affect the safety of vehicles, and how lighter vehicles might affect the safety of drivers and pas sengers in the entire on-road fleet, as we are analyzing potential future CAFE and GHG standards. The agencies seek to ensure that the standards are designed to encourage manufacturers t o pursue a path toward compliance that is
both cost-effective and safe.

To estimate the possible safety effects of the MY 2 017-2025 standards, then, the agencies have undertaken research that approaches this quest ion from several angles. First, we are using a statistical approach to study the effect of vehicle mass reduction on safety historically, as discussed in greater detail in section C below. St atistical analysis is performed using the most recent historical crash data available, and is cons idered as the agencies’ best estimate of potential mass-safety effects. The agencies recognize that ne gative safety effects estimated based on the historical relationships could potentially be tempe red with safety technology advances in the future, and may not represent the current or future fleet. Second, we are using an engineering approach to investigate what amount of mass reducti on is affordable and feasible while maintaining vehicle safety and other major function alities such as NVH and acceleration performance. Third, we are also studying the new c hallenges these lighter vehicles might bring to vehicle safety and potential countermeasures ava ilable to manage those challenges effectively.

The sections below discuss more specifically the st ate of the research on the mass-safety relationship, and how the agencies integrate that r esearch into our assessment of the potential safety effects of the MY 2017-2025 CAFE and GHG sta ndards.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 4 of 32 3. What is the current state of the research on statis tical analysis of historical crash
data?

a. Background

Researchers have been using statistical analysis to examine the relationship of vehicle mass and safety in historical crash data for many y ears, and continue to refine their techniques over time. In the MY 2012-2016 final rule, the age ncies stated that we would conduct further study and research into the interaction of mass, si ze and safety to assist future rulemakings, and start to work collaboratively by developing an inte ragency working group between NHTSA, EPA, DOE, and CARB to evaluate all aspects of mass, size and safety. The team would seek to coordinate government supported studies and indepen dent research, to the greatest extent possible, to help ensure the work is complementary to previous and ongoing research and to guide further research in this area.

The agencies also identified three specific areas t o direct research in preparation for future CAFE/GHG rulemaking in regards to statistica l analysis of historical data.

First, NHTSA would contract with an independent ins titution to review the statistical methods that NHTSA and DRI have used to analyze his torical data related to mass, size and safety, and to provide recommendation on whether th e existing methods or other methods should be used for future statistical analysis of historic al data. This study will include a consideration of potential near multicollinearity in the historical data and how best to address it in a regression analysis. The 2010 NHTSA report was also peer revi ewed by two other experts in the safety field - Charles Farmer (Insurance Institute for Hig hway Safety) and Anders Lie (Swedish Transport Administration). 6

Second, NHTSA and EPA, in consultation with DOE, wo uld update the MYs 1991–1999 database on which the safety analyses in the NPRM a nd final rule are based with newer vehicle data, and create a common database that could be ma de publicly available to help address concerns that differences in data were leading to d ifferent results in statistical analyses by
different researchers.

And third, in order to assess if the design of rece nt model year vehicles that incorporate
various mass reduction methods affect the relations hips among vehicle mass, size and safety, the agencies sought to identify vehicles that are using material substitution and smart design, and to try to assess if there is sufficient crash data inv olving those vehicles for statistical analysis. If sufficient data exists, statistical analysis would be conducted to compare the relationship among

6 All three of the peer reviews are in docket, NHTSA -2010-0152. You can access the docket at http://www.regulations.gov/#!home by typing ‘NHTSA-2010-0152’ where it says “enter k eyword or ID” and then clicking on “Search.”*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 5 of 32 mass, size and safety of these smart design vehicle s to vehicles of similar size and mass with more traditional designs.

Significant progress has been made on these tasks s ince the MY 2012-2016 final rule, as follows: The independent review of recent and updat ed statistical analyses of the relationship between vehicle mass, size, and crash fatality rate s has been completed. NHTSA contracted with the University of Michigan Transportation Research Institute (UMTRI) to conduct this review, and the UMTRI team led by Paul Green evaluated over 20 papers, including studies done by NHTSA’s Charles Kahane, Tom Wenzel of the US Depart ment of Energy’s Lawrence Berkeley National Laboratory, Dynamic Research, Inc., and ot hers. UMTRI’s basic findings will be
discussed below. Some commenters in recent CAFE ru lemakings, including some vehicle manufacturers, suggested that the designs and mater ials of more recent model year vehicles may
have weakened the historical statistical relationsh ips between mass, size, and safety. The agencies agree that the statistical analysis would be improved by using an updated database that reflects more recent safety technologies, vehicle d esigns and materials, and reflects changes in the overall vehicle fleet. The agencies also belie ve, as UMTRI also found, that different statistical analyses may have had different results because they each used slightly different datasets for their analyses. In order to try to mi tigate this problem and to support the current rulemaking, NHTSA has created a common, updated dat abase for statistical analysis that consists of crash data of model years 2000-2007 vehicles in calendar years 2002-2008, as compared to the database used in prior NHTSA analyses which was based on model years 1991–1999 vehicles in calendar years 1995-2000. The new data base is the most up-to-date possible, given the processing lead time for crash data and the nee d for enough crash cases to permit statistically meaningful analyses. NHTSA has made the new databa ses available to the public, 7 enabling other researchers to analyze the same data and hope fully minimizing discrepancies in the results
that would have been due to inconsistencies across databases. 8 The agencies recognize, however, that the updated database may not represen t the future fleet, because vehicles have continued and will continue to change.

The agencies are aware that several studies have be en initiated using NHTSA’s 2011 newly established safety database. In addition to a new Kahane study, which is discussed in section II.G.4, other on-going studies include two by Wenzel at Lawrence Berkeley National Laboratory (LBNL) under contract with the U.S. DOE, and one by Dynamic Research, Inc. (DRI) contracted by the International Council on Cl ean Transportation (ICCT). These studies may take somewhat different approaches to examine t he statistical relationship between fatality risk, vehicle mass and size. In addition to a deta iled assessment of the NHTSA 2011 report, Wenzel is expected to consider the effect of mass a nd footprint reduction on casualty risk per crash, using data from thirteen states. Casualty r isk includes both fatalities and serious or

7 The new databases are available at http://www.nhts a.gov/fuel-economy (look for “Download Crash Databa ses for Statistical Analysis of Relationships Between Vehic les’ Fatality Risk, Mass, and Footprint.”

8 75 Fed. Reg. 25324 (May 7, 2010); the discussion o f planned statistical analyses is on pp. 25395-2539 6.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 6 of 32 incapacitating injuries. DRI is expected to use a two-stage approach to separate the effect of mass reduction on two components of fatality risk, crash avoidance and crashworthiness. The LBNL assessment of the NHTSA 2011 report is availab le in the docket for this NPRM. 9 The casualty risk effect study was not available in tim e to inform this NPRM. The completed final peer reviewed-report on both assessments will be av ailable prior to the final rule. DRI has also indicated that it expects its study to be publicly available prior to the final rule. The agencies wil l consider these studies and any others that become a vailable, and the results may influence the safety analysis for the final rule.

Other researchers are free to download the database from NHTSA’s website, and we expect to see additional papers in the coming month s and as comments to the rulemaking that may also inform our consideration of these issues f or the final rule. Kahane’s updated study for 2011 is currently undergoing peer-review, and is av ailable in the docket for this rulemaking for review by commenters.

Finally, EPA and NHTSA with DOT’s Volpe Center, par t of the Research and Innovative Technology Administration (RITA), attempted to inve stigate the implications of “Smart Design,” by identifying and describing the types of “Smart D esign” and methods for using “Smart Design” to result in vehicle mass reduction, select ing analytical pairs of vehicles, and using the appropriate crash database to analyze vehicle crash data. The analysis identified several onevehicle and two-vehicle crash datasets with the pot ential to shed light on the issue, but the available data for specific crash scenarios was ins ufficient to produce consistent results that could be used to support conclusions regarding hist orical performance of “smart designs.”

Undertaking these tasks has helped the agencies com e closer to resolving some of the ongoing debates in statistical analysis research of historical crash data. We intend to apply these conclusions going forward, and we believe that the public discussion of the issues will be facilitated by the research conducted. The followi ng sections discuss the findings from these studies and others in greater detail, to present a more nuanced picture of the current state of the
statistical research.

b. NHTSA workshop on vehicle mass, size and safety

On February 25, 2011, NHTSA hosted a workshop on ma ss reduction, vehicle size, and fleet safety at the Headquarters of the U.S. Depart ment of Transportation in Washington, DC. 10
The purpose of the workshop was to provide the agen cies with a broad understanding of current research in the field and provide stakeholders and the public with an opportunity to weigh in on

9 –Wenzel, T.P. (2011b). Assessment of NHTSA’s Report “Relationships between Fatality Risk, Mass, and Footprint in Model Year 2000-2007 Passenger Cars an d LTVs” , available at...

10 A video recording, transcript, and the presentati ons from the NHTSA workshop on mass reduction, vehi cle size and fleet safety is available at http://www.nhtsa.gov/fuel-economy (look for “NHTSA Workshop on Vehicle MassSize-Safety on Feb. 25”)*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 7 of 32 this issue. NHTSA also created a public docket to receive comments from interested parties that
were unable to attend.

The speakers included Charles Kahane of NHTSA, Tom Wenzel of Lawrence Berkeley National Laboratory, R. Michael Van Auken of Dynami c Research Inc. (DRI), Jeya Padmanaban of JP Research, Inc., Adrian Lund of the Insurance Institute for Highway Safety, Paul Green of the University of Michigan Transportation Research Institute (UMTRI), Stephen Summers of NHTSA, Gregg Peterson of Lotus Engineering, Koichi Kamiji of Honda, John German of the International Council on Clean Transportation (ICCT ), Scott Schmidt of the Alliance of Automobile Manufacturers, Guy Nusholtz of Chrysler, and Frank Field of the Massachusetts Institute of Technology.

The wide participation in the workshop allowed the agencies to hear from a broad range of experts and stakeholders. The contributions wer e particularly relevant to the agencies’ analysis of the effects of weight reduction for thi s proposed rule. The presentations were divided into two sessions that addressed the two expansive sets of issues – statistical evidence of the roles of mass and size on safety, and engineering r ealities – structural crashworthiness, occupant injury and advanced vehicle design.

The first session focused on previous and ongoing s tatistical studies of crash data that attempt to identify the relative effects of vehicle mass and size on fleet safety. There was consensus that there is a complicated relationship with many confounding influences in the data. Wenzel summarized a recent study he conducted compa ring four types of risk (fatality or casualty risk, per vehicle registration-years or pe r crash) using police-reported crash data from
five states. 11 He showed that the trends in risk for various cla sses of vehicles (e.g., non-sports car passenger cars, vans, SUVs, crossover SUVs, pic kups) were similar regardless of what risk was being measured (fatality or casualty) or what e xposure metric was used (e.g., registration years, police-reported crashes, etc.). In general, most trends showed a lower risk for drivers of larger, heavier vehicles.

Although Wenzel’s analysis was focused on differenc es in the four types of risk on the relative risk by vehicle type, he cautioned that, w hen analyzing casualty risk per crash, analysts should control for driver age and gender, crash loc ation (urban vs. rural), and the state in which the crash occurred (to account for crash reporting biases).

Several participants pointed out that analyses must also control for individual technologies with significant safety effects (e.g., Electronic Stability Control, airbags).It was not always conclusive whether a specialty vehicle group (e.g., sports cars, two-door cars, early crossover SUVs) were outliers that confound the tre nd or unique datasets that isolate specific

11 Wenzel, T.P. (2011a). Analysis of Casualty Risk per Police-Reported Crash for Model Year 2000 to 2004 Vehicles, using Crash Data from Five States , March 2011, LBNL-4897E, available at: http://eetd.lbl.gov/EA/teepa/pub.html#Vehicle*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 8 of 32 vehicle characteristics. Unfortunately, specialty v ehicle groups are usually adopted by specific driver groups, often with outlying vehicle usage or driver behavior patterns. Green, who conducted an independent review of the previous sta tistical analyses, suggested that evaluating residuals will give an indication of whether or not a data subset can be legitimately removed without inappropriately affecting the analytical re sults.

It was recognized that the physics of a two-vehicle crash require that the lighter vehicle experience a greater change in velocity, which ofte n leads to disproportionately more injury risk. Lund noted persistent historical trends that, in an y time period, occupants of the smallest and lightest vehicles had, on average, fatality rates a pproximately twice those of occupants of the largest and heaviest vehicles but predicted “the sk y will not fall” as the fleet downsizes, we will not see an increase in absolute injury risk because smaller cars will become increasingly protective of their occupants. Padmanaban also not ed in her research of the historical trends that mass ratio and vehicle stiffness are significant pr edictors with mass ratio consistently the dominant parameter when correlating harm. Reducing the mass of any vehicle may have competing societal effects as it increases the inju ry risk in the lightened vehicle and decreases them in the partner vehicle

The separation of key parameters was also discussed as a challenge to the analyses, as vehicle size has historically been highly correlate d with vehicle mass. Presenters had varying approaches for dealing with the potential multicoll inearity between these two variables. Van
Auken of DRI stated that there was latitude in the value of Variance Inflation Factor (VIF, a measure of multicollinearity) that would call resul ts into question, and suggested that the large value of VIF for curb weight might imply “perhaps t he effect of weight is too small in comparison to other factors.” Green, of UMTRI, sta ted that highly correlated variables may not be appropriate for use in a predictive model and th at “match[ing] on footprint” (i.e., conducting multiple analyses for data subsets with similar foo tprint values) may be the most effective way to
resolve the issue.

There was no consensus on the overall effect of the maneuverability of smaller, lighter vehicles. German noted that lighter vehicles shoul d have improved handling and braking characteristics and “may be more likely to avoid co llisions”. Lund presented crash involvement data that implied that, among vehicles of similar f unction and use rates, crash risk does not go down for more “nimble” vehicles. Several presenter s noted the difficulties of projecting past data into the future as new technologies will be us ed that were not available when the data were collected. The advances in technology through the d ecades have dramatically improved safety for all weight and size classes. A video of IIHS’s 50 th anniversary crash test of a 1959 Chevrolet Bel Air and 2009 Chevrolet Malibu graphically demon strated that stark differences in design and technology that can possibly mask the discrete mass effects, while videos of compatibility crash tests between smaller, lighter vehicles and contemp orary larger, heavier vehicles graphically showed the significance of vehicle mass and size.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 9 of 32 Kahane presented results from his 2010 report 12 that found that a scenario which took
some mass out of heavier vehicles but little or no mass out of the lightest vehicles did not impact safety in absolute terms. Kahane noted that if the analyses were able to consider the mass of both vehicles in a two-vehicle crash, the results m ay be more indicative of future crashes. There is apparent consistency with other presentations (e .g., Padmanaban, Nusholtz) that reducing the overall ranges of masses and mass ratios seems to r educe overall societal harm. That is, the effect of mass reduction exclusively does not appear to be a “zero sum game” in which any increase in harm to occupants of the lightened vehicle is preci sely offset by a decrease in harm to the occupants of the partner vehicle. If the mass of t he heavier vehicle is reduced by a larger percentage, the changes in velocity from the collis ion are more nearly equal and the injuries suffered in the lighter vehicle are likely to be re duced more than the injuries in the heavier vehicle are increased. Alternatively, a fixed mass reduction (say, 100 lbs) in all vehicles could increase societal harm whereas a fixed percentage m ass reduction is more likely to be neutral.

Padmanaban described a series of studies conducted in recent years. She included numerous vehicle parameters including bumper height and several measures of vehicle size and stiffness and also commented on previous analyses t hat using weight and wheelbase together in a logistic model distorts the estimates, resulting in inflated variance with wrong signs and magnitudes in the results. Her results consistently showed that vehicle mass ratio was a more important parameter than those describing vehicle g eometry or stiffness. Her ultimate conclusion was that removing mass (e.g., 100 lbs.) from all passenger cars would cause an
overall increase in fatalities in truck-to-car cras hes while removing the same amount from light
trucks would cause an overall decrease in fatalitie s.

c. Report by Green et al., UMTRI – “Independent Review : Statistical Analyses of Relationship Between Vehicle Curb Weight, Track Wid th, Wheelbase and Fatality Rates,” April 2011.

As explained above, NHTSA contracted with the Unive rsity of Michigan Transportation Research Institute (UMTRI) to conduct an independen t review 13 of a set of statistical analyses of relationships between vehicle curb weight, the foot print variables (track width, wheelbase) and fatality rates from vehicle crashes. The purpose of this review was to examine analysis methods, data sources, and assumptions of the statistical st udies, with the objective of identifying the reasons for any differences in results. Another obj ective was to examine the suitability of the various methods for estimating the fatality risks o f future vehicles.

12 Kahane, C. J. (2010). “Relationships Between Fatali ty Risk, Mass, and Footprint in Model Year 1991-199 9 and Other Passenger Cars and LTVs,” Final Regulatory Impact Analysis: Corporate Average Fuel Economy for MY 2012-MY 2016 Passenger Cars and Light Trucks . Washington, DC: National Highway Traffic Safety Administration, pp. 464-542, available at http://www.nhtsa.gov/staticfiles/rulemaking/pdf/caf e/CAFE_2012- 2016_FRIA_04012010.pdf

.

13 The review is independent in the sense that it was conducted by an outside third party without any in terest in the reported outcome.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 10 of 32 UMTRI reviewed a set of papers, reports, and manus cripts provided by NHTSA (listed in Appendix A of UMTRI’s report, which is a vailable in the docket to this rulemaking) that examined the statistical relationships between fatality or casualty rates and vehicle properties such as curb weight, track width, wheelbase and oth er variables.

It is difficult to summarize a study of that lengt h and complexity for purposes of this discussion, but fundamentally, the UMTRI team concl uded the following:

• Differences in data may have complicated comparison s of earlier analyses, but if the methodology is robust, and the methods were applied in a similar way, small changes in data should not lead to different conclusions. The main conclusions and findings should be reproducible. The data base created by Kahane a ppears to be an impressive collection of files from appropriate sources and the best ones available for answering the research questions considered in this study.

• In statistical analysis simpler models generally le ad to improved inference, assuming the data and model assumptions are appropriate. In tha t regard, the disaggregate logistic regression model used by NHTSA in the 2003 report 14 seems to be the most appropriate model, and valid for the analysis in the context th at it was used: finding general associations between fatality risk and mass – and t he general directions of the reported associations are correct.

• The two-stage logistic regression model in combinat ion with the two-step aggregate regression used by DRI seems to be more complicated than is necessary based on the data being analyzed, and summing regression coefficients from two separate models to arrive at conclusions about the effects of reductions in w eight or size on fatality risk seems to add unneeded complexity to the problem.

• One of the biggest issues regarding this work is th e historical correlation between curb weight, wheelbase, and track width. Including thre e variables that are highly correlated in the same model can have adverse effects on the f it of the model, especially with respect to the parameter estimates, as discussed by Kahane. UMTRI makes no conclusions about multicollinearity, other than to say that inferences made in the presence of multicollinearity should be judged with great caution. At the NHTSA workshop on size, safety and mass, Paul Green sugge sted that a matched analysis, in which regressions are run on the relationship betwe en mass reduction and risk separately for vehicles of similar footprint, could be underta ken to investigate the effect of multicollinearity between vehicle mass and size. K ahane has combined wheelbase and track width into one variable (footprint) to compar e with curb weight. NHTSA believes that the 2011 Kahane analysis has done all it can t o lessen concerns about multicollinearity, but a concern still exists. In considering other studies provided by NHTSA for evaluation by the UMTRI team:

o Papers by Wenzel, and Wenzel and Ross, addressing a ssociations between fatality risk per vehicle registration-year, weight, and siz e by vehicle model contribute to understanding some of the relationships between ris k, weight, and size. However, least squares linear regression models, without mod ification, are not exposure-*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 11 of 32 based risk models and inference drawn from these mo dels tends to be weak since they do not account for additional differences in v ehicles, drivers, or crash conditions that could explain the variance in risk by vehicle model.

o A 2009 J.P. Research paper focused on the difficult ies associated with separating out the contributions of weight and size variables when analyzing fatality risk properly recognized the problem arising from multic ollinearity and included a clear explanation of why fatality risk is expected to increase with increasing mass ratio. UMTRI concluded that the increases in fatal ity risk associated with a 100- pound reduction in weight allowing footprint to var y with weight as estimated by Kahane and JP Research, are broadly more convincing than the 6.7 percent reduction in fatality risk associated with mass red uction while holding footprint constant, as reported by DRI.

o A paper by Nusholtz et al. focused on the question of whether vehicle size can reasonably be the dominant vehicle factor for fatal ity risk, and finding that changing the mean mass of the vehicle population (l eaving variability unchanged) has a stronger influence on fatality risk than corr esponding (feasible) changes in mean vehicle dimensions, concluded unequivocally th at reducing vehicle mass while maintaining constant vehicle dimensions will increase fatality risk. UMTRI concluded that if one accepts the methodology, this conclusion is robust against realistic changes that may be made in the force vs. deflection characteristics of the impacting vehicles.

o Two papers by Robertson, one a commentary paper and the other a peer-reviewed journal article, were reviewed. The commentary pap er did not fit separate models according to crash type, and included passenger car s, vans, and SUVs in the same model. UMTRI concluded that some of the claims in t he commentary paper appear to be overstated, and intermediate results a nd more documentation would help the reader determine if these claims are valid . The second paper focused largely on the effects of electronic stability cont rol (ESC), but generally followed on from the first paper except that curb weight is not fit and fuel economy is used as a surrogate.

The UMTRI study provided a number of useful suggest ions that Kahane considered in updating his 2011 analysis, and that have been inco rporated into the safety effects estimates for the current rulemaking.

d. Report by Dr. Charles Kahane, NHTSA – “Relationship s Between Fatality Risk, Mass, and Footprint in Model Year 2000-2007 Passeng er Cars and LTVs,” 2011

The relationship between a vehicle’s mass, size, an d fatality risk is complex, and it varies in different types of crashes. NHTSA, along with o thers, has been examining this relationship for over a decade. The safety chapter of NHTSA’s A pril 2010 final regulatory impact analysis (FRIA) of CAFE standards for MY 2012-2016 passenger cars and light trucks included a statistical analysis of relationships between fatal ity risk, mass, and footprint in MY 1991-1999 passenger cars and LTVs (light trucks and vans), ba sed on calendar year (CY) 1995-2000 crash*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 12 of 32 and vehicle-registration data. 15 The 2010 analysis used the same data as the 2003 analysis, but included vehicle mass and footprint in the same reg ression model.

The principal findings of NHTSA’s 2010 analysis wer e that mass reduction in lighter cars, even while holding footprint constant, would significantly increase societal fatality risk,
whereas mass reduction in the heavier LTVs would si gnificantly reduce net societal fatality risk, because it would reduce the fatality risk of occupa nts in lighter vehicles which collide with the heavier LTVs. NHTSA concluded that, as a result, a ny reasonable combination of mass reductions while holding footprint constant in MY 2 012-2016 vehicles – concentrated, at least to some extent, in the heavier LTVs and limited in the lighter cars – would likely be approximately safety-neutral; it would not significantly increase fatalities and might well decrease them.

NHTSA’s 2010 report partially agreed and partially disagreed with analyses published during 2003-2005 by Dynamic Research, Inc. (DRI). NHTSA and DRI both found a significant protective effect for footprint, and that reducing mass and footprint together (downsizing) on smaller vehicles was harmful. DRI’s analyses estim ated a significant overall reduction in fatalities from mass reduction in all light-duty ve hicles if wheelbase and track width were maintained, whereas NHTSA’s report showed overall f atality reductions only in the heavier LTVs, and benefits only in some types of crashes fo r other vehicle types. Much of NHTSA’s 2010 report, as well as recent work by DRI, involve d sensitivity tests on the databases and models, which generated a range of estimates somewh ere between the initial DRI and NHTSA
results. 16

Immediately after issuing the final rule for MYs 20 12-2016 CAFE and GHG standards in May 2010, NHTSA and EPA began work on the next join t rulemaking to develop CAFE and GHG standards for MY 2017 to 2025 and beyond. The preamble to the 2012-2016 final rule stated that NHTSA, working closely with EPA and the Department of Energy (DOE), would perform a new statistical analysis of the relations hips between fatality rates, mass and footprint, updating the crash and exposure databases to the la test available model years, refining the

15 Kahane, C. J. (2010). “Relationships Between Fatal ity Risk, Mass, and Footprint in Model Year 1991-19 99 and Other Passenger Cars and LTVs,” Final Regulatory Impact Analysis: Corporate Average Fuel Economy for MY 2012-MY 2016 Passenger Cars and Light Trucks . Washington, DC: National Highway Traffic Safety Administration, pp. 464-542, available at http://www.nhtsa.gov/staticfiles/rulemaking/pdf/caf e/CAFE_2012- 2016_FRIA_04012010.pdf

. 16 Van Auken, R. M., and Zellner, J. W. (2003). A Further Assessment of the Effects of Vehicle Weig ht and Size Parameters on Fatality Risk in Model Year 1985-98 P assenger Cars and 1986-97 Light Trucks . Report No. DRITR-03-01. Torrance, CA: Dynamic Research, Inc.; Van Auken, R. M., and Zellner, J. W. (2005a). An Assessment of the Effects of Vehicle Weight and Size on Fatality Risk in 1985 to 1998 Model Year Passenger Cars and 1985 to 1997 Model Year Light Trucks and Vans . Paper No. 2005-01-1354. Warrendale, PA: Society of Automotive Engineers; Van Auken, R. M., and Zellner, J. W. (20 05b). Supplemental Results on the Independent Effects of Curb Weight, Wheelbase, and Track on Fatality Risk in 19 85-1998 Model Year Passenger Cars and 1986-97 Model Year
LTVs . Report No. DRI-TR-05-01. Torrance, CA: Dynamic R esearch, Inc.; Van Auken, R.M., and Zellner, J. W. (2011). “Updated Analysis of the Effects of Passen ger Vehicle Size and Weight on Safety,” NHTSA Workshop on Vehicle Mass-Size-Safety , Washington, February 25, 2011, http://www.nhtsa.gov/staticfiles/rulemaking/pdf/MSS /MSSworkshop_VanAuken.pdf*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 13 of 32 methodology in response to peer reviews of the 2010 report and taking into account changes in vehicle technologies. The previous databases of MY 1991-1999 vehicles in CY 1995-2000 crashes has become outdated as new safety technolog ies, vehicle designs and materials were introduced. The new databases comprising MY 2000-2 007 vehicles in CY 2002-2008 crashes with the most up-to-date possible, given the proces sing lead time for crash data and the need for enough crash cases to permit statistically meaningf ul analyses. NHTSA has made the new databases available to the public 17 , enabling other researchers to analyze the same da ta and hopefully minimizing discrepancies in the results d ue to inconsistencies across the data used. 18

One way to estimate these effects is via statistica l analyses of societal fatality rates per vehicle miles traveled (VMT), by vehicles’ mass and footprint, for the current on-road vehicle fleet. The basic analytical method used for the 20 11 NHTSA report is the same as in NHTSA’s 2010 report: cross-sectional analyses of the effect of mass and footprint reductions on the
societal fatality rate per billion vehicle miles of travel (VMT), while controlling for driver age and gender, vehicle type, vehicle safety features, crash times and locations, and other factors. Separate logistic regression models are run for thr ee types of vehicles and nine types of crashes. Societal fatality rates include occupants of all ve hicles in the crash, as well as non-occupants, such as pedestrians and cyclists. NHTSA’s 2011 Rep ort 19 analyzes MY 2000-2007 cars and LTVs in CY 2002-2008 crashes. Fatality rates were derived from FARS data, 13 State crash files, and registration and mileage data from R.L. Polk.

The most noticeable change in MY 2000-2007 vehicles from MY 1991-1999 has been the increase in crossover utility vehicles (CUV), w hich are SUVs of unibody construction, often but not always built upon a platform shared with pa ssenger cars. CUVs have blurred the distinction between cars and trucks. The new analy sis treats CUVs and minivans as a separate vehicle class, because they differ in some respects from pickup-truck-based LTVs and in other respects from passenger cars. In the 2010 report, the many different types of LTVs were combined into a single analysis and NHTSA believes that this may have made the analyses too complex and might have contributed to some of the u ncertainty in the results.

The new database has accurate VMT estimates, derive d from a file of odometer readings by make, model, and model year recently developed b y R.L. Polk and purchased by NHTSA. 20
For the 2011 report, the relative distribution of c rash types has been changed to reflect the projected distribution of crashes during the period from 2017 to 2025, based on the estimated effectiveness of electronic stability control (ESC) in reduction the number of fatalities in rollover crashes and crashes with a stationary object. The a nnual target population of fatalities or the

17 http://www.nhtsa.gov/fuel-economy

18 75 Fed. Reg. 25324 (May 7, 2010); the discussion o f planned statistical analyses is on pp. 25395-2539 6.

19 Kahane, C. J. (2011). “Relationships Between Fatal ity Risk, Mass, and Footprint in Model Year 2000-20 07 Passenger Cars and LTVs,”, July 2011. The report i s available in the NHTSA docket, NHTSA-2010-0152. Y ou can access the docket at http://www.regulations.gov/#!home by typing ‘NHTSA-2010-0152’ where it says “enter keyword or ID” and then clicking on “Search.”

20 In the 1991-1999 data base, VMT was estimated only by vehicle class, based on NASS CDS data.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 14 of 32 annual fatality distribution baseline 21 was not decreased in the period between 2017 and 2 025 for the safety statistics analysis, but is taken into a ccount later in the Volpe model analysis, since all vehicles in the future will be equipped with ESC 22

.
For the 2011 report, vehicles are now grouped into five classes rather than four: passenger cars (including both 2-door and 4-door ca rs) are split in half by median weight; CUVs and minivans; and truck-based LTVs, which are also split in half by median weight of the model year 2000-2007 vehicles. Table Error! No text of specified style in document. -1 presents the estimated percent increase in U.S. societal fatalit y risk per ten billion VMT for each 100-pound reduction in vehicle mass, while holding footprint constant, for each of the five classes of
vehicles.

Table Error! No text of specified style in document. -1 Results of 2011 NHTSA report Fatality Increase (%) per 100-Pound Mass Reduction While Holding Footprint Constant

MY 2000-2007 CY 2002-2008 Fatality Increase (%) Per 100-Pound Mass Reduction While Holding Footprint Constant

Point Estimate 95% Confidence Bounds

Cars < 3,106 pounds 1.44 + .29 to +2.59
Cars > 3,106 pounds .47 - .58 to +1.52 CUVs and minivans - .46 -1.75 to + .83 Truck-based LTVs < 4,594 pounds .52 - .43 to +1.46
Truck-based LTVs > 4,594 pounds - .39 -1.06 to + .27

Only the 1.44 percent risk increase in the lighter cars is statistically significant. There are non-significant increases in the heavier cars and t he lighter truck-based LTVs, and nonsignificant societal benefits for mass reduction in CUVs, minivans, and the heavier truck-based LTVs. Based on these results, potential combinatio ns of mass reductions that maintain footprint and are proportionately somewhat higher for the hea vier vehicles may be safety-neutral or better as point estimates and, in any case, unlikely to si gnificantly increase fatalities. The primarily non-significant results are not due to a paucity of data, but because the societal effect of mass reduction while maintaining footprint, if any, is s mall.

MY 2000-2007 vehicles of all types are heavier and larger than their MY 1991-1999 counterparts. The average mass of passenger cars i ncreased by 5 percent from 2000 to 2007 and the average mass of pickup trucks increased by 19 p ercent. Other types of vehicles became heavier, on the average, by intermediate amounts. There are several reasons for these increases:

21 MY 2004 -2007 vehicles with fatal crashes occurred in CY 2004-2008 are selected as the annual fatalit y distribution baseline in the Kahane analysis.

22 In the Volpe model, NHTSA assumed that the safety trend would result in 12.6 percent reduction betwee n 2007 and 2020 due to the combination of ESC, new safety standard, and behavior changes anticipated.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 15 of 32 during this time frame, some of the lighter make-mo dels were discontinued; many models were redesigned to be heavier and larger; and consumers more often selected stretched versions such as crew cabs in their new-vehicle purchases.

It is interesting to compare the new results to NHT SA’s 2010 analysis of MY 1991-1999 vehicles in CY 1995-2000, especially the new point estimate to the “actual regression result scenario” in the 2010 report:

Table Error! No text of specified style in document. -2 2010 Report: MY 1991-1999, CY 1995-2000 Fatality Increase (%) per 100-Pound Ma ss Reduction While Holding Footprint Constant

Actual Regression Result Scenario Upper-Estimate Scenario Lower-Estimate

Scenario Cars < 2,950 pounds 2.21 2.21 1.02
Cars > 2,950 pounds 0.90 0.90 0.44 LTVs < 3,870 pounds 0.17 0.55 0.41
LTVs > 3,870 pounds -1.90 -0.62 -0.73

Table Error! No text of specified style in document. -3 Fatality Increase (%) per 100- Pound Mass Reduction While Holding Footprint Consta nt

NHTSA (2010) NHTSA (2011)

Lighter cars 2.21% 1.43%

Heavier cars 0.89% 0.48% Lighter LTVs 0.17%* 0.52%

Heavier LTVs -1.90%* -0.40%

CUV/ minivan -0.47%

*Includes CUV/minivan

The new results are directionally the same as in 20 10: fatality increase in the lighter cars, safety benefit in the heavier LTVs, but the effects may have become weaker at both ends. (The agencies do not consider this conclusion to be defi nitive because of the relatively wide confidence bounds of the estimates.) The fatality increase in the lighter cars tapered off from 2.21 percent to 1.44 percent while the societal ben efit of mass reduction in the heaviest LTVs diminished from 1.90 percent to 0.39 percent and is no longer statistically significant.

The agencies believe that the changes may be due to a combination of both changes in the
characteristics of newer vehicles and revisions to the analysis. NHTSA believes, above all, that several light, small car models with poor safety pe rformance were discontinued by 2000 or during 2000-2007. Also, the tendency of light, sma ll vehicles to be driven poorly is not as strong as it used to be – perhaps in part because safety i mprovements in lighter and smaller vehicles*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 16 of 32 have made some good drivers more willing to buy the m. Both agencies believe that at the other end of the weight/size spectrum, blocker beams and other voluntary compatibility improvements in LTVs, as well as compatibility-related self-prot ection improvements to cars, have made the heavier LTVs less aggressive in collisions with lig hter vehicles (although the effect of mass disparity remains). This report’s analysis of CUVs and minivans as a separate class of vehicles may have relieved some inaccuracies in the 2010 reg ression results for LTVs. Interestingly, the new actual-regression results are quite close to th e previous report’s “lower-estimate scenario,” which was an attempt to adjust for supposed inaccur acies in some regressions and for a seemingly excessive trend toward higher crash rates in smaller and lighter cars.

The principal difference between the heavier vehicl es, especially truck-based LTVs, and the lighter vehicles, especially passenger cars, is that mass reduction has a different effect in
collisions with another car or LTV. When two vehic les of unequal mass collide, the delta V is higher in the lighter vehicle, in the same proporti on as the mass ratio. As a result, the fatality risk is also higher. Removing some mass from the h eavy vehicle reduces delta V in the lighter vehicle, where fatality risk is high, resulting in a large benefit, offset by a small penalty because delta V increases in the heavy vehicle, where fatal ity risk is low – adding up to a net societal benefit. Removing some mass from the lighter vehi cle results in a large penalty offset by a small benefit – adding up to net harm. These consi derations drive the overall result: fatality increase in the lighter cars, reduction in the heav ier LTVs, and little effect in the intermediate groups. However, in some types of crashes, especia lly first event rollovers and impacts with fixed objects, mass reduction is usually not harmfu l and often beneficial, because the lighter vehicles respond more quickly to braking and steeri ng and are often more stable because their center of gravity is lower. Offsetting that benefi t is the continuing historical tendency of lighter
and smaller vehicles to be driven less well – altho ugh it continues to be unknown why that is so, and to what extent, if any, the lightness or smalln ess of the vehicle contributes to people driving it less safely.

The estimates of the model are formulated for each 100-pound reduction in mass; in other words, if risk increases by 1 percent for 100 pound s reduction in mass, it would increase by 2 percent for a 200-pound reduction, and 3 percent fo r a 300-pound reduction (more exactly, 2.01 percent and 3.03 percent, because the effects work like compound interest). Confidence bounds around the point estimates will grow wider by the s ame proportions.

The regression results are best suited to predict t he effect of a small change in mass, leaving all other factors, including footprint, the same. With each additional change from the current environment, the model may become somewhat less accurate and it is difficult to assess the sensitivity to additional mass reduction greate r than 100 pounds. The agencies recognize that the light-duty vehicle fleet in the 2017-2025 timef rame will be different than the 2000-2007 fleet analyzed for this study. Nevertheless, one conside ration provides some basis for confidence.
This is NHTSA’s fourth evaluation of the effects of mass reduction and/or downsizing, comprising databases ranging from MY 1985 to 2007. The results of the four studies are not*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 17 of 32 identical, but they have been consistent up to a po int. During this time period, many makes and models have increased substantially in mass, someti mes as much as 30-40 percent. 23 If the statistical analysis has, over the past years, been able to accommodate mass increases of this magnitude, perhaps it will also succeed in modeling the effects of mass reductions on the order of 10-20 percent, if they occur in the future.

e. Report by Tom Wenzel, LBNL, “An Assessment of NHTSA ’s Report ‘Relationships Between Fatality Risk, Mass, and Foo tprint in Model Year 2000- 2007 Passenger Cars and LTVs’”, 2011

DOE contracted with Tom Wenzel of Lawrence Berkeley National Laboratory to conduct an assessment of NHTSA’s updated 2011 study of the effect of mass and footprint reductions on US fatality risk per vehicle miles traveled, and to provide an analysis of the effect of mass and footprint reduction on casualty risk per police-rep orted crash, using independent data from thirteen states. The assessment has been completed and reviewed by NHTSA and EPA staff, and
a draft final version is included in the docket of today’s rulemaking; the separate analysis of crash data from thirteen states will be completed a nd included in the docket shortly. Both reports will be peer reviewed by outside experts.

The LBNL report replicates Kahane’s analysis for NH TSA, using the same data and methods, and in many cases using the same SAS progr ams. The Wenzel report finds that although mass reduction in lighter (less than 3,106 lbs) cars leads to a statistically significant 1.44% increase in fatality risk per vehicle miles t ravelled (VMT), the increase is small. He tests this result for sensitivity to changes in specifica tions of the regression models and what data are
used. In addition Wenzel shows that there is a wid e range in fatality rates by vehicle model for models that have the same mass, even after accounti ng for differences in drivers’ age and gender, safety features installed, and crash times and loca tions. This section summarizes the results of
the Wenzel assessment of the most recent NHTSA anal ysis.

The LBNL report highlights the effect of the other driver, vehicle, and crash control variables, in addition to the effect of mass and fo otprint reduction, on risk. Some of the other variables NHTSA included in its regression models h ave much larger effects on fatality risk than mass or footprint reduction. For example, the mode ls indicate that a 100-lb increase in the mass of a lighter car results in a 1.44% reduction in fa tality risk; this is the largest estimated effect o f changes in vehicle mass, and the only one that is s tatistically significant. For comparison this reduction in fatality risk could also be achieved b y a 13% increase in 4-door sedans equipped
with ESC.

23 For example, one of the most popular models of sma ll 4-door sedans increased in curb weight from 1,93 9 pounds in MY 1985 to 2,766 pounds in MY 2007, a 43 percent increase. A high-sales mid-size sedan grew from 2 ,385 to 3,354 pounds (41%); a best-selling pickup truck fro m 3,390 to 4,742 pounds (40%) in the basic model wi th 2-door cab and rear-wheel drive; and a popular minivan fro m 2,940 to 3,862 pounds (31%).*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 18 of 32 The 1.44% increase in risk from reducing mass in th e lighter cars was tested for sensitivity changes in the specification of, or the data used in, the regression models. For example, using the current distribution of crashes, rather than adjusting the distribution to that expected after full adoption of ESC, reduces the ef fect to 1.18%; excluding the calendar year variables from the model, which may be weakening th e modeled benefits of vehicle safety technologies, reduces the effect to 1.39%; and incl uding vehicle make in the model increases the
effect to 1.81%. The results also are sensitive to the selection of data to include in the analysis: excluding bad drivers increases the effect to 2.03% , while excluding crashes involving alcohol or drugs increases the effect to 1.66%, and including sports, police, and all-wheel drive cars increases the effect to 1.64%. Finally, changing t he definition of risk also affects the result for lighter cars: using the number of fatalities per in duced exposure crash reduces the effect to - 0.24% (that is, a 0.24% reduction in risk), while u sing the number of fatal crashes (rather than total fatalities) per VMT increases the effect to 1 .84%. These sensitivity tests, except one, changed the estimated coefficient by less than 1 pe rcentage point, which is within its statistical confidence bounds of 0.29 to 2.59 percent and may b e considered compatible with the baseline result. Using two or more variables that are strong ly correlated in the same regression model (referred to as multicollinearity) can lead to inac curate results. However, the correlation between vehicle mass and footprint may not be strong enough to cause serious concern. Experts suggest that a correlation of greater than 0.60 (or a varia nce inflation factor of 2.5) raises concern about multicollinearity. 24 The correlation between vehicle mass and footprin t ranges from over 0.80 for four-door sedans, pickups, and SUVs, to about 0 .65 for two-door cars and CUVs, to 0.26 for minivans; when pickups and SUVs are considered toge ther, the correlation between mass and footprint is 0.65. Wenzel notes that the 2011 NHTS A report recognizes that the “near” multicollinearity between mass and footprint may no t be strong enough to invalidate the results from a regression model that includes both variable s. In addition, NHTSA included several analyses to address possible effects of the near-mu lticollinearity between mass and footprint.

First, NHTSA ran a sensitivity model specification, where footprint is not held constant, but rather allowed to vary as mass varies (i.e. NHT SA ran a regression model which includes mass but not footprint). If the multicollinearity was so great that including both variables in the same model gave misleading results, removing footpr int from the model could give mass coefficients five or more percentage points differe nt than keeping it in the model. NHTSA’s sensitivity test indicates that when footprint is a llowed to vary with mass, the effect of mass
reduction on risk increases from 1.44% to 2.64% for lighter cars, and from a non-significant 0.47% to a statistically-significant 1.94% for heav er cars (changes of less than two percentage points); however, the effect of mass reduction on l ight trucks is unchanged, and is still not statistically significant for CUVs/minivans.

24 Light-Duty Vehicle Greenhouse Gas Emission Standar ds and Corporate Average Fuel Economy Standards; Final Rule, April 1, 2010, Section II.G. 3., page 139.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 19 of 32 Second, NHTSA conducted a stratification analysis o f the effect of mass reduction on risk by dividing vehicles into deciles based on the ir footprint, and running a separate regression model for each vehicle and crash type, for each foo tprint decile (3 vehicle types times 9 crash types times 10 deciles equals 270 regressions). Th is analysis estimates the effect of mass reduction on risk separately for vehicles with simi lar footprint. The analysis indicates that mass reduction does not consistently increase risk acros s all footprint deciles for any combination of vehicle type and crash type. Mass reduction increa ses risk in a majority of footprint deciles for 13 of the 27 crash and vehicle combinations, but fe w of these increases are statistically significant. On the other hand, mass reduction dec reases risk in a majority of footprint deciles for 9 of the 27 crash and vehicle combinations; in some cases these risk reductions are large and statistically significant. 25 If reducing vehicle mass while maintaining footpr int inherently leads to an increase in risk, the coefficients on mass re duction should be more consistently positive, and with a larger R 2 , across the 27 vehicle/crash combinations, than sh own in the analysis. These findings are consistent with the conclusion o f the basic regression analyses, namely, that the effect of mass reduction while holding footprin t constant, if any, is small.

One limitation of using logistic regression to esti mate the effect of mass reduction on risk
is that a standard statistic to measure the extent to which the variables in the model explain the range in risk, equivalent to the R 2 statistic in a linear regression model, does not e xist. (SAS does generate a pseudo-R 2 value for logistic regression models; in almost al l of the NHTSA regression models this value is less than 0.10). F or this reason LBNL conducted an analysis of risk versus mass by vehicle model. LBNL used the r esults of the NHTSA logistic regression model to predict the number of fatalities expected after accounting for all vehicle, driver, and crash variables included in the NHTSA regression mo del except for vehicle weight and footprint. LBNL then plotted expected fatality risk per VMT by vehicle model against the mass of each model, and analyzed the change in risk as mass incr eases, as well as how much of the change in risk was explained by all of the variables included in the model.

The analysis indicates that, after accounting for a ll the variables, risk does decrease as mass increases; however, risk and mass are not stro ngly correlated, with the R 2 ranging from
0.33 for CUVs to less than 0.15 for all other vehic le types (as shown in Figure x). This means that, on average, risk decreases as mass increases, but the variation in risk among individual vehicle models is stronger than the trend in risk f rom light to heavy vehicles. For fullsize (i.e. 3⁄4- and 1-ton) pickups, risk increases as mass increase s, with an R 2 of 0.43, consistent with NHTSA’s basic regression results for the heavier LT Vs (societal risk increases as mass increases). LBNL also examined the relationship be tween residual risk, that is the remaining unexplained risk after accounting for all vehicle, driver and crash variables, and mass, and found similarly poor correlations. This implies that the remaining factors not included in the regression

25 And in 5 of the 27 crash and vehicle combinations, mass reduction increased risk in 5 deciles and dec reased risk in 5 deciles.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 20 of 32 model that account for the observed range in risk b y vehicle model also are not correlated with mass. (LBNL found similar results when the analysi s compared risk to vehicle footprint.)

Figure Error! No text of specified style in document. -1 indicates that some vehicles on the road today have the same, or lower, fatality ra tes than models that weigh substantially more, and are substantially larger in terms of footprint. After accounting for differences in driver age and gender, safety features installed, and crash ti mes and locations, there are numerous examples of different models with similar weight and footpri nt yet widely varying fatality rates. The variation of fatality rates among individual models may reflect differences in vehicle design,
differences in the drivers who choose such vehicles (beyond what can be explained by demographic variables such as age and gender), and statistical variation of fatality rates based on
limited data for individual models. Differences in vehicle design can, and already do, mitigate some safety penalties from reduced mass; this is co nsistent with NHTSA’s opinion that some of the changes in its regression results between the 2 003 study and the 2011 study are due to the redesign or removal of certain smaller and lighter models of poor design.

Figure Error! No text of specified style in document. -1 Predicted US fatality risk per VMT vs. curb weight by vehicle type, after accounti ng for all driver, crash, and vehicle variables except mass and footprint

f. Based on this information, what do the agencies con sider to be the current state of statistical research on vehicle mass and safety?

The agencies believe that statistical analysis of h istorical crash data continues to be an informative and important tool in assessing the pot ential safety impacts of the proposed R2 = 0.12

R2 = 0.04
R2 = 0.00
R2 = 0.43
R2 = 0.05 R2 = 0.33
R2 = 0.09 0 40 80 120 160 200 240 280 320 360 400

2000 2400 2800 3200 3600 4000 4400 4800 5200 5600 6 000 6400 6800 7200 7600Predicted US fatality risk (crash fdatalities per 1010VMT)

Curb weight (lbs) 2-dr cars
4-dr cars Small pickups Fullsize pickups SUVs
CUVs
Minivans*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 21 of 32 standards. The effect of mass reduction while main taining footprint is a complicated topic and there are open questions whether future designs wil l reduce the historical correlation between weight and size. It is important to note that whil e the updated database represents more current vehicles with technologies more representative of v ehicles on the road today, they still do not fully represent what vehicles will be on the road i n the 2017-2025 timeframe. The vehicles
manufactured in the 2000-2007 timeframe were not su bject to footprint-based fuel economy standards. The agencies expect that the attribute- based standards will likely facilitate the design of vehicles such that manufacturers may reduce mass while maintaining footprint. Therefore, it is possible that the analysis for 2000-2007 vehicles m ay not be fully representative of the vehicles that will be on the road in 2017 and beyond.

While we recognize that statistical analysis of his torical crash data may not be the only way to think about the future relationship between vehicle mass and safety, we also recognize that other assessment methods are also subject to u ncertainties, which makes statistical analysis of historical data an important starting point if e mployed mindfully and recognized for how it can be useful and what its limitations may be.

NHTSA undertook the independent review of statistic al studies and held the mass-safety workshop in February 2011 in order to help the agen cies sort through the ongoing debates over what statistical analysis of historical data is act ually telling us. Previously, the agencies have assumed that differences in results were due in par t to inconsistent databases; by creating the updated common database and making it publicly avai lable, we are hopeful that that aspect of the problem has been resolved, and moreover, the UMTRI review suggested that differences in data were probably less significant than the agencies ma y have thought. Statistical analyses of historical crash data should be examined for potent ial multicollinearity issues. The agencies will continue to monitor issues with multicollinearity i n our analyses, and hope that outside researchers will do the same. And finally, based o n the findings of the independent review, the agencies continue to be confident that Kahane’s ana lysis is one of the best for the purpose of analyzing potential safety effects of future CAFE a nd GHG standards. UMTRI concluded that Kahane’s approach is valid, and Kahane has continue d and refined that approach for the current analysis. The NHTSA 2011 statistical fatality repor t finds directionally similar but less statistically significant relationships between veh icle mass, size, and footprint, as discussed above. Based on these findings, the agencies belie ve that in the future, fatalities due to mass
reduction will be best reduced if mass reduction is concentrated in the heaviest vehicles. NHTSA considers part of the reason that more recent historical data shows a dampened effect in the relationship between mass reduction and safety is that all vehicles, including traditionally lighter ones, grew heavier during that timeframe (2 000s). As lighter vehicles might become more prevalent in the fleet again over the next dec ade, it is possible that the trend could strengthen again. On the other hand, extensive use of new lightweight materials and optimized vehicle design may weaken the relationship. Future updated analyses will be necessary to
determine how the effect of mass reduction on risk changes over time.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 22 of 32 Both agencies agree that there are several identifi able safety trends already in place or expected to occur in the foreseeable future that ar e not accounted for in the study, since they
were not in effect at the time that the vehicles in question were manufactured. For example, there are two important new safety standards that h ave already been issued and will be phasing in after MY 2008. FMVSS No. 126 (49 CFR § 571.126) re quires electronic stability control in all new vehicles by MY 2012, and the upgrade to FMVSS N o. 214 (Side Impact Protection, 49 CFR § 571.214) will likely result in all new vehicles b eing equipped with head-curtain air bags by MY 2014. Additionally, we anticipate continued imp rovements in driver (and passenger) behavior, such as higher safety belt use rates. Al l of these may tend to reduce the absolute number of fatalities. On the other hand, as crash a voidance technology improves, future statistical analysis of historical data may be comp licated by a lower number of crashes. In summary, the agencies have relied on the coefficien ts in the Kahane 2011 study for estimating the potential safety effects of the proposed CAFE a nd GHG standards for MYs 2017-2025, based on our assumptions regarding the amount of mass red uction that could be used to meet the standards in a cost-effective way without adversely affecting safety. Section E below discusses the methodology used by the agencies in more detail ; while the results of the safety effects analysis are less significant than the results in t he MY 2012-2016 final rule, the agencies still believe that any statistically significant results warrant careful consideration of the assumptions about appropriate levels of mass reduction on which to base future CAFE and GHG standards, and have acted accordingly in developing the propos ed standards.

4. How do the agencies think technological solutions m ight affect the safety estimates indicated by the statistical analysis?

As mass reduction becomes a more important technolo gy option for manufacturers in meeting future CAFE and GHG standards, manufacturer s will invest more and more resources in developing increasingly lightweight vehicle designs that meet their needs for manufacturability and the public’s need for vehicles that are also sa fe, useful, affordable, and enjoyable to drive. There are many different ways to reduce mass, as di scussed in Chapter 3 of this TSD and in Sections II, III, and IV of the preamble, and a con siderable amount of information is available today on lightweight vehicle designs currently in p roduction and that may be able to be put into production in the rulemaking timeframe. Discussion of lightweight material designs from NHTSA’s workshop is presented below.

Besides “lightweighting” technologies themselves, t hough, there are a number of considerations when attempting to evaluate how futu re technological developments might affect the safety estimates indicated by the statistical a nalysis. As discussed in the first part of this chapter, for example, careful changes in design and /or materials used might mitigate some of the potential decrease in safety from mass reduction – through improved distribution of crash pulse energy, etc. – but these techniques can sometimes c ause other problems, such as increased crash forces on vehicle occupants that have to be mitigat ed, or greater aggressivity against other*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 23 of 32 vehicles in crashes. Manufacturers may develop new and better restraints – air bags, seat belts, etc. – to protect occupants in lighter vehicles in crashes, but NHTSA’s current safety standards for restraint systems are designed based on the cur rent fleet, not the yet-unknown future fleet. The agency will need to monitor trends in the crash data to see whether changes to the safety standards (or new safety standards) become necessar y. Manufacturers are also increasingly investigating a variety of crash avoidance technolo gies – ABS, electronic stability control (ESC), lane departure warnings, vehicle-to-vehicle (V2V) c ommunications – that, as they become more prevalent in the fleet, are expected to reduce the number of overall crashes, and fatal, crashes. Until these technologies are present in the fleet i n greater numbers, however, it will be difficult to assess whether they can mitigate the observed re lationship between vehicle mass and safety in
the historical data.

Along with the California Air Resources Board (CARB ), the agencies have initiated several projects to estimate the maximum potential for advanced materials and improved designs to reduce mass in the MY 2017-2021 timeframe, while continuing to meeting safety regulations and maintaining functionality of vehicles. Another NHTSA-sponsored study will estimate the effects of these design changes on overall fleet sa fety.

A. NHTSA has awarded a contract to Electricore, with E DAG and George Washington University (GWU) as subcontractors, to study the ma ximum feasible amount of mass reduction for a mid-size car – specifically, a Hond a Accord. The study tore down a MY 2011 Honda Accord, studied each component and sub-s ystem, and then redesigned each component and sub-system trying to maximize the amo unt of mass reduction with technologies that are considered feasible for 200,0 00 units per year production volume during the time frame of this rulemaking. Electric ore and its sub-contractors are consulting industry leaders and experts for each co mponent and sub-system when deciding which technologies are feasible. Electric ore and its sub-contractors are also building detailed CAD/CAE/powertrain models to vali date vehicle safety, stiffness, NVH, durability, drivability and powertrain performance. For OEM-supplied parts, a detailed cost model is being built based on a Technical Cost Modeling (TCM) approach developed by the Massachusetts Institute of Technology (MIT) Materials Systems Laboratory’s research 26 to estimate the costs to OEMs for manufacturing pa rts. The cost will be broken down into each of the operations involved in the ma nufacturing; for example, for a sheet metal part, production costs will be estimated from the blanking of the steel coil to the final operation to fabricate the component. Total costs are then categorized into fixed cost, such as tooling, equipment, and facilities; a nd variable costs such as labor, material, energy, and maintenance. These costs will be assess ed through an interactive process between the product designer, manufacturing enginee rs, and cost analysts. For OEMpurchased parts, the cost will be estimated by cons ultation with experienced cost analysts and Tier 1 system suppliers. This study will help t o inform the agencies about the feasible

26 Frank Field, Randolph Kirchain and Richard Roth, P rocess cost modeling: Strategic engineering and eco nomic evaluation of materials technologies, JOM Journal o f the Minerals, Metals and Materials Society, Volum e 59, Number 10, 21-32. Available at http://msl.mit.edu/pubs/docs/Field_KirchainCM_Strat EvalMatls.pdf (last accessed Aug. 22, 2011).*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 24 of 32 amount of mass reduction and the cost associated wi th it. NHTSA intends to have this study completed and peer reviewed before July 2012, in time for it to play an integral role in informing the final rule.

B. EPA has awarded a similar contract to FEV, with EDA G and Monroe & Associates, Inc. as subcontractors, to study the maximum feasible am ount of mass reduction for a mid-size CUV (cross over vehicle) specifically, a Toyota Ven za. The study tears down a MY 2010 vehicle, studies each component and sub-system, and then redesigns each component and sub-system trying to maximize the amount of mass re duction with technologies that are considered feasible for high volume production for a 2017 MY vehicle. FEV in coordination with EDAG is building detailed CAD/CAE /powertrain models to validate vehicle safety, stiffness, NVH, durability, drivabi lity and powertrain performance to assess the safety of this new design. This study bu ilds upon the low development (20% mass reduction) design in the 2010 Lotus Engineerin g study “An Assessment of Mass Reduction Opportunities for a 2017-2020 Model Year Vehicle Program”. This study builds upon the low development (20% mass reduction ) design in the 2010 Lotus Engineering study “An Assessment of Mass Reduction Opportunities for a 2017-2020 Model Year Vehicle Program”. This study will underg o a peer review. EPA intends to have this study completed and peer reviewed before July 2012, in time for it to play an integral role in informing the final rule.

C. California Air Resources Board (CARB) has awarded a contract to Lotus Engineering, to study the maximum feasible amount of mass reduction for a mid-size CUV (cross over vehicle) specifically, a Toyota Venza. The study w ill concentrate on the Body-in-White and closures in the high development design (40% ma ss reduction) in the Lotus Engineering study cited above. The study will provi de an updated design with crash simulation, detailed costing and manufacturing feas ibility of these two systems for a MY2020 high volume production vehicle. This study w ill undergo a peer review. EPA intends to have this study completed and peer revie wed before July 2012, in time for it to play an integral role in informing the final rule.

D. NHTSA has contracted with George Washington Univers ity (GWU) to build a fleet simulation model to study the impact and relationsh ip of light-weight vehicle design and injuries and fatalities. This study will also incl ude an evaluation of potential countermeasures to reduce any safety concerns assoc iated with lightweight vehicles. NHTSA will include three light-weighted vehicle des igns in this study: the one from Electricore/EDAG/GWU mentioned above, one from Lotu s Engineering funded by California Air Resource Board for the second phase of the study, evaluating mass reduction levels around 35 percent of total vehicle mass, and two funded by EPA and the International Council on Clean Transportation (ICCT ). This study will help to inform the agencies about the possible safety implications for light-weight vehicle designs and the appropriate counter-measures, 27 if applicable, for these designs, as well as the f easible amounts of mass reduction. All of these analyses a re expected to be finished and peerreviewed before July 2012, in time to inform the fi nal rule.

27 Countermeasures could potentially involve improved front end structure, knee bags, seat ramps, buckle pretensioners, and others.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 25 of 32 a. NHTSA workshop on vehicle mass, size and safety

As stated above, in section C.2, on February 25, 20 11, NHTSA hosted a workshop on mass reduction, vehicle size, and fleet safety at t he Headquarters of the US Department of Transportation in Washington, DC. The purpose of t he workshop was to provide the agencies with a broad understanding of current research in t he field and provide stakeholders and the public with an opportunity to weigh in on this issu e. The agencies also created a public docket to receive comments from interested parties that we re unable to attend. The presentations were
divided into two sessions that addressed the two ex pansive sets of issues. The first session explored statistical evidence of the roles of mass and size on safety, and is summarized in section C.2. The second session explored the engineering r ealities of structural crashworthiness, occupant injury and advanced vehicle design, and is summarized here. The speakers in the second session included Stephen Summers of NHTSA, G regg Peterson of Lotus Engineering, Koichi Kamiji of Honda, John German of the Internat ional Council on Clean Transportation (ICCT), Scott Schmidt of the Alliance of Automobile Manufacturers, Guy Nusholtz of Chrysler,
and Frank Field of the Massachusetts Institute of T echnology.

The second session explored what degree of weight r eduction and occupant protection are feasible from technical, economic, and manufacturin g perspectives. Field emphasized that technical feasibility alone does not constitute fea sibility in the context of vehicle mass reduction. Sufficient material production capacity and viable manufacturing processes are essential to economic feasibility. Both Kamiji and German noted that both good materials and good designs will be necessary to reduce fatalities. For example , German cited the examples of hexagonally structured aluminum columns, such as used in the Ho nda Insight, that can improve crash absorption at lower mass, and of high-strength stee l components that can both reduce weight and improve safety. Kamiji made the point that widespre ad mass reduction will reduce the kinetic energy of all crashes which should produce some ben eficial effect.

Summers described NHTSA’s plans for a model to esti mate fleetwide safety effects based on an array of vehicle-to-vehicle computation al crash simulations of current and anticipated vehicle designs. In particular, three c omputational models of lightweight vehicles are under development. They are based on current vehic les that have been modified to substantially reduce mass. The most ambitious was the “high deve lopment” derivative of a Toyota Venza developed by Lotus Engineering and discussed by Mr. Peterson. Its structure currently contains about 75% aluminum, 12% magnesium, 8% steel, and 5% advanced composites. Peterson expressed confidence that the design had the potent ial to meet federal safety standards. Nusholtz emphasized that computational crash simulations inv olving more advanced materials were less reliable than those involving traditional metals su ch as aluminum and steel.

Nusholtz presented a revised data-based fleet safet y model in which important vehicle parameters were modeled based on trends from curren t NCAP crash tests. For example, crash pulses and potential intrusion for a particular siz e vehicle were based on existing distributions.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 26 of 32 Average occupant deceleration was used to estimate injury risk. Through a range of simulations of modified vehicle fleets, he was able to estimate the net effects of various design strategies for lighter weight vehicles, such as various scaling ap proaches for vehicle stiffness or intrusion. The approaches were selected based on engineering requi rements for modified vehicles. Transition
from the current fleet was considered. He concluded that protocols resulting in safer transitions (e.g., removing more mass from heavier vehicles wit h appropriate stiffness scaling according to a 3/2 power law) were not generally consistent with t hose that provide the greatest reduction in GHG production.

German discussed several important points on the fu ture of mass reduction. Similar to
Kahane’s discussion of the difficulties of isolatin g the impact of weight reduction, German stated that other important variables, such as vehicle des ign and compatibility factors, must be held constant in order for size or weight impacts to be quantified in statistical analyses. He presented results that, compared to driver, driving influence s, and vehicle design influences, the safety impacts of size and weight are small and difficult to quantify. He noted that several scenarios, such as rollovers, greatly favored the occupants of smaller and lighter cars once a crash occurred. He pointed out that if size and design are maintain ed, lower weight should translate into a lower total crash force. He thought that advanced materi al designs have the potential to “decouple” the
historical correlation between vehicle size and wei ght, and felt that effective design and driver attributes may start to dominate size and weight is sues in future vehicle models.

Other presenters noted industry’s perspective of th e effect of incentivizing weight reduction. Field highlighted the complexity of ins titutional changes that may be necessitated by weight reduction, including redesign of material an d component supply chains and manufacturing infrastructure. Schmidt described an industry perspective on the complicated decisions that must be made in the face of regulato ry change, such as evaluating goals, gains, and timing.

Field and Schmidt noted that the introduction of te chnical innovations is generally an innate development process involving both tactical and strategic considerations that balance
desired vehicle attributes with economic and techni cal risk. In the absence of challenging regulatory requirements, a substantial technology c hange is often implemented in stages, starting with lower volume pilot production before a commitm ent is made to the infrastructure and supply chain modifications necessary for inclusion on a high-volume production model. Joining, damage characterization, durability, repair, and si gnificant uncertainty in final component costs are also concerns. Thus, for example, the widesprea d implementation of high-volume composite or magnesium structures might be problematic in the short or medium term when compared to relatively transparent aluminum or high strength st eel implementations. Regulatory changes will
affect how these tradeoffs are made and these risks are managed.

Koichi Kamiji presented data showing in increased u se of high strength steel in their Honda product line to reduced vehicle mass and incr ease vehicle safety. He stated that mass*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 27 of 32 reduction is clearly a benefit in 42% of all fatal crashes because absolute energy is reduced. He followed up with slides showing the application of certain optimized it designs can improve safety even when controlling for weight and size.

A philosophical theme developed that explored the e thics of consciously allowing the
total societal harm associated with mass reduction to approach the anticipated benefits of enhanced safety technologies. Although some partic ipants agreed that there may eventually be specific fatalities that would not have occurred wi thout downsizing, many also agreed that safety strategies will have to be adapted to the reality c reated by consumer choices, and that “We will
be ok if we let data on what works – not wishful th inking – guide our strategies.”

5. How have the agencies estimated safety effects for the proposed standards?

a. What was the agencies’ methodology for estimating s afety effects for the proposed standards?

As explained above, the agencies consider the 2011 statistical analysis of historical crash data by NHTSA to represent the best estimates of th e potential relationship between mass reduction and fatality increases in the future flee t. This section discusses how the agencies used NHTSA’s 2011 analysis to calculate specific estimat es of safety effects of the proposed standards, based on the analysis of how much mass r eduction manufacturers might use to meet the proposed standards.

Neither the proposed CAFE/GHG standards nor the age ncies’ analysis mandates mass reduction, or mandates that mass reduction occur in any specific manner. However, mass reduction is one of the technology applications ava ilable to the manufacturers and a degree of mass reduction is used by both agencies’ models to determine the capabilities of manufacturers and to predict both cost and fuel consumption/emiss ions impacts of improved CAFE/GHG
standards. We note that the amount of mass reducti on selected for this rulemaking is based on our assumptions about how much is technologically f easible without compromising safety.
While we are confident that manufacturers will buil d safe vehicles, we cannot predict with certainty that they will choose to reduce mass in e xactly the ways that the agencies have analyzed in response to the standards. In the even t that manufacturers ultimately choose to reduce mass and/or footprint in ways not analyzed o r anticipated by the agencies, the safety effects of the rulemaking may likely differ from th e agencies’ estimates.

NHTSA utilized the 2011 Kahane study relationships between weight and safety, expressed as percent changes in fatalities per 100- pound weight reduction while holding footprint constant. However, as mentioned previous ly, there are several identifiable safety trends already occurring, or expected to occur in the fore seeable future, that are not accounted for in the study. For example, the two important new safety s tandards that were discussed above for electronic stability control and head curtain airba gs, have already been issued and began phasing*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 28 of 32 in after MY 2008. The recent shifts in market shar es from pickups and SUVs to cars and CUVs may continue, or accelerate, if gasoline prices rem ain high, or rise further. The growth in vehicle miles travelled may continue to stagnate if the eco nomy does not improve, or gasoline prices remain high. And improvements in driver (and passe nger) behavior, such as higher safety belt use rates, may continue. All of these will tend to reduce the absolute number of fatalities in the future. The agency estimated the overall change in fatalities by calendar year after adjusting for ESC, Side Impact Protection, and other Federal safe ty standards and behavioral changes projected through this time period. The smaller pe rcent changes in risk from mass reduction (from the 2011 NHTSA analysis), coupled with the re duced number of baseline fatalities, results
in smaller absolute increases in fatalities than th ose predicted in the 2010 rulemaking.

NHTSA examined the impacts of identifiable safety t rends over the lifetime of the vehicles produced in each model year. An estimate of these impacts was contained in a previous
agency report. 28 The impacts were estimated on a year-by-year basi s, but could be examined in a combined fashion. Using this method, we estimate a 12.6 percent reduction in fatality levels between 2007 and 2020 for the combination of safety standards and behavioral changes anticipated (ESC, head-curtain air bags, and increa sed belt use). Since the same safety standards are taking effect in the same years, the estimates derived from applying NHTSA fatality percentages to a baseline of 2007 fatalities were t hus multiplied by 0.874 to account for changes that NHTSA believes will take place in passenger ca r and light truck safety between the 2007 baseline on-road fleet used for this particular saf ety analysis and year 2025.

To estimate the amount of mass reduction to apply i n the rulemaking analysis, the agencies considered fleet safety effects for mass r eduction. As previously discussed and shown
in Error! Reference source not found. , the Kahane 2011 study shows that applying mass reduction to CUVs and light duty trucks will genera lly decrease societal fatalities, while applying mass reduction to passenger cars will increase fata lities. The CAFE model uses coefficients from the Kahane study along with the mass reduction level applied to each vehicle model to project societal fatality effects in each model yea r. NHTSA used the CAFE model and conducted iterative modeling runs varying the maxim um amount of mass reduction applied to each subclass in order to identify a combination th at achieved a high level of overall fleet mass reduction while not adversely affecting overall fle et safety. These maximum levels of mass
reduction for each subclass were then used in the C AFE model for the rulemaking analysis. The agencies believe that mass reduction of up to 20 pe rcent is feasible on light trucks, CUVs and

ls technologies, JOM Journal of the Minerals, Metal s and Materials Society, Volume 59, Number 10, 21-3 2. Available at http://msl.mit.edu/pubs/docs/Field_KirchainCM_Strat EvalMatls.pdf (last accessed Aug. 22, 2011).

28 Countermeasures could potentially involve improved front end structure, knee bags, seat ramps, buckle pretensioners, and others.

28 Blincoe, L. and Shankar, U, “The Impact of Safety Standards and Behavioral Trends on Motor Vehicle Fa tality Rates,” DOT HS 810 777, January 2007. See Table 4 comparing 2020 to 2007 (37,906/43,363 = 12.6% reduc tion (1-.126 = .874). Since 2008 was a recession year, it does not seem appropriate to use that as a basel ine. We believe this same ratio should hold for this analysis which should compare 2025 to 2008. Thus, we are inclin ed to continue to use the same ratio.*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 29 of 32 minivans, 29 but that less mass reduction should be implemente d on other vehicle types to avoid increases in societal fatalities.. For this propos al, NHTSA used the mass reduction levels shown
in Table Error! No text of specified style in document. -4.

Table Error! No text of specified style in document. -15 Mass Reduction Levels Applied in CAFE Model

Absolute % Subcompact

and Subcompact Perf. PC Compact

and Compact Perf. PC Midsize PC

and Midsize Perf. PC Large PC

and Large Perf. PC Minivan LT Small, Midsize and Large LT

MR1* 0.0% 2.0% 1.5% 1.5% 1.5% 1.5%

MR2 0.0% 0.0% 5.0% 7.5% 7.5% 7.5%
MR3 0.0% 0.0% 0.0% 10.0% 10.0% 10.0%

MR4 0.0% 0.0% 0.0% 0.0% 15.0% 15.0%

MR5 0.0% 0.0% 0.0% 0.0% 20.0% 20.0%

Notes:

*MR1-MR5: different levels of mass reduction used i n CAFE model

After applying the mass reduction levels in the CAF E model, Table Error ! No text of specified style in document. -5 shows the results of NHTSA’s safety analysis sep arately for each model year. 30 These are estimated increases or decreases in fat alities over the lifetime of the model year fleet. A positive number means that fat alities are projected to increase, a negative number (indicated by parentheses) means that fatali ties are projected to decrease. The results are significantly affected by the assumptions put into the Volpe model to take more weight out of the heavy LTVs, CUVs, and minivans than out of other ve hicles. As the negative coefficients only appear for LTVs greater than 4,594 lbs., CUVs, and minivans, a statistically improvement in safety can only occur if more weight is taken out o f these vehicles than passenger cars or smaller light trucks. Combining passenger car and light tru ck safety estimates for the proposed standards
results in an increase in fatalities over the lifet ime of the nine model years of MY 2017-2025 of 4 fatalities, broken up into an increase of 61 fatali ties in passenger cars and 56 decrease in fatalitie s in light trucks. NHTSA also analyzed the results f or different regulatory alternatives in Chapter IX of its PRIA; the difference in the results by al ternative depends upon how much weight reduction is used in that alternative and the types and sizes of vehicles that the weight reduction applies to.

29 When applying mass reduction, NHSTA capped the max imum amount of mass reduction to 20 percent for any individual vehicle class. The 20 percent ca p is the maximum amount of mass reduction the agenc ies believe to be feasible in MYs 2017-2025 time frame.

30 NHTSA has changed the definitions of a passenger c ar and light truck for fuel economy purposes betwee n the time of the Kahane 2003 analysis and this final rul e. About 1.4 million 2 wheel drive SUVs have been redefined as passenger cars instead of light trucks. The Kahane 2011 analysis continues with the definitions used in the Kahane 2003 analysis. Thus, there are different definitio ns between Tables IX-1 and IX-2 (which use the old definitions) and Table IX-3 (which uses the new definitions).*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 30 of 32 Table Error! No text of specified style in document. -5 NHTSA Calculated MassSafety-Related Fatality Impacts of the Proposed Sta ndards over the Lifetime of the

Vehicles Produced in each Model Year

MY 2017 MY 2018 MY 2019 MY 2020 MY 2021 MY 2022 MY 2023 MY 2024 MY 2025 Total

Passenger

cars (2) (0) 11 16 15 13 12 1 (2) 63

Light trucks 3 (7) 0 (13) (8) (15) (12) (8) 0 (56)

Total 1 (8) 12 3 7 (2) 0 (8) (2) 4

Using the same coefficients from the 2011 Kahane st udy, EPA used the OMEGA model to conduct a similar analysis. After applying thes e percentage increases to the estimated weight reductions per vehicle size by model year assumed i n the Omega model, Table Error! No text of specified style in document. -6 shows the results of EPA’s safety analysis separ ately for each model year. These are estimated increases or decre ases in fatalities over the lifetime of the model year fleet. A positive number means that fat alities are projected to increase; a negative number means that fatalities are projected to decre ase. For details, see the EPA RIA Chapter 3.

Table Error! No text of specified style in document. -6 EPA Calculated Mass-SafetyRelated Fatality Impacts of the Proposed Standards over the Lifetime of the Vehicles Produced in each Model Year

MY 2017 MY 2018 MY 2019 MY 2020 MY 2021 MY 2022 MY 2023 MY 2024 MY 2025 Total

Passenger

cars -3 -5 -8 -11 -14 8 32 58 86 143

Light trucks -1 -1 -2 -2 -4 -35 -67 -99 -133 -343

Total -3 -7 -10 -13 -18 -27 -34 -41 -47 -201

b. Why might the real-world effects be less than or gr eater than what the agencies
have calculated?

As discussed above the ways in which future technol ogical advances could potentially mitigate the safety effects estimated for this rule making: lightweight vehicles could be designed to be both stronger and not more aggressive; restra int systems could be improved to deal with higher crash pulses in lighter vehicles; crash avoi dance technologies could reduce the number of overall crashes; roofs could be strengthened to imp rove safety in rollovers. As also stated above, however, while we are confident that manufacturers will strive to build safe vehicles, it will be*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 31 of 32 difficult for both the agencies and the industry to know with certainty ahead of time how crash trends will change in the future fleet as lightweig hted vehicles become more prevalent. We will have to continue to monitor the crash data going fo rward.

Additionally, we note that the total amount of mass reduction used in the agencies’ analysis for this rulemaking were chosen based on o ur assumptions about how much is technologically feasible without compromising safet y. Again, while we are confident that manufacturers are motivated to build safe vehicles, we cannot predict with certainty that they will choose to reduce mass in exactly the ways that the agencies have analyzed in response to the
standards. In the event that manufacturers ultimat ely choose to reduce mass and/or footprint in ways not analyzed by the agencies, the safety effec ts of the rulemaking may likely differ from the agencies’ estimates.

The agencies acknowledge it is possible that a manu facturer could theoretically “game” a footprint-based standard by redesigning a vehicle t o increase wheelbase and/or track width. However, as NHTSA explained in promulgating MY 2008 -2011 light truck CAFE standards and MY 2011 passenger car and light truck CAFE standard s, and as the agencies jointly explained in promulgating MY 2012-2016 CAFE and GHG standards, t he agencies believe that such engineering changes are significant enough to be un attractive as a measure to undertake solely to reduce compliance burdens. Similarly, the agencies acknowledge that a manufacturer could, without actually reengineering specific vehicles to increase footprint, shift production toward those that perform well compared to their respectiv e footprint-based targets. However, as NHTSA and, more recently NHTSA and EPA have previou sly explained, because such production shifts would run counter to market deman ds, they would also be competitively unattractive. Based on this regulatory design, the analysis assumes this proposal will not have
either of the effects described above.

As discussed in Chapter 2 of the Draft Joint TSD, t he agencies note that the standard is flat for vehicles smaller than 41 square feet and t hat downsizing in this category could help achieve overall compliance, if the vehicles are des irable to consumers. The agencies note that only xxxx percent of MY2008 passenger cars were bel ow 41 square feet, and due to the overall lower level of utility of these vehicles, and the e ngineering challenges involved in ensuring that these vehicles meet all applicable federal motor ve hicle safety standards (FMVSS), we expect a significant increase in this segment of the market in the future is unlikely. Please see Chapter 2
of the Draft Joint TSD for additional discussion. We seek comment on the appropriateness of the overa ll analytic assumption that the attribute-based aspect of the proposed standards wi ll have no effect on the overall distribution of vehicle footprints. Notwithstanding the agencies’ current judgment that such deliberate reengineering or production shift are unlikely as p ure compliance strategies, both agencies are considering the potential future application of veh icle choice models, and anticipate that doing so
could result in estimates that market shifts induce d by changes in vehicle prices and fuel*** E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review ***

Page 32 of 32 economy levels could lead to changes in fleet’s foo tprint distribution. However, neither agency is currently able to include vehicle choice modelin g in our analysis.

c. Do the agencies plan to make any changes in these e stimates for the final rule?

As discussed above, the agencies have based our est imates of safety effects due to the proposed standards on Kahane’s 2011 report. That r eport is currently undergoing peer review and is docketed for public review; 31 the peer review comments and response to peer revi ew comments, along with any revisions to the report in response to that review, will also be docketed there. Depending on the results of the pe er review, our calculation of safety effects for the final rule will also be revised accordingly. T he agencies will also consider any comments received on the proposed rule, and determine at tha t time whether and how our estimates should be changed in response to those comments. Addition al studies published by the agencies or other independent researchers as previously discuss ed will also be considered, along with any
other relevant information.

31 Kahane, C. J. (2011). “Relationships Between Fatali ty Risk, Mass, and Footprint in Model Year 2000-200 7 Passenger Cars and LTVs,”, July 2011. The report i s available in the NHTSA docket, NHTSA-2010-0152. Y ou can access the docket at http://www.regulations.gov/#!home by typing ‘NHTSA-2010-0152’ where it says “enter keyword or ID” and then clicking on “Search.”