July 14, 2011 

Mr. Cleophas Jackson 

Assistant Division Director 

Compliance and Innovative Strategies Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

2565 Plymouth Road 

Ann Arbor, MI 48105 

Subject: Heavy-Duty Hybrid Powertrain Systems and Heavy

Diagnostic Requirements 

Dear Mr. Jackson: 

Eaton Corporation is a member of the Hybrid Manufacturers Regulatory Collaboration 

(HMRC). The HMRC was formed to bring together companies involved in the heavy

hybrid vehicle industry for purposes of addressing common issues associated with 

regulations affecting hybrid vehicles. HMRC’s other current members are Allison 

Transmission, Inc., and BAE Systems Inc.

HMRC would like to express its sincere appreciation to you and your staff at EPA for 

addressing issues that have recently become apparent regarding heavy

powertrain systems and heavy

strongly believe that your actions will make it possible to avoid a serious disruption of the 

hybrid heavy-duty vehicle industry and adverse impacts on the market for such vehicles. 

This in turn will ensure the viability of heavy

role in allowing compliance with the Greenhouse Gas Emissions Standards and Fuel 

Efficiency Standards for Medium

promulgated by EPA. 

In addition, HMRC appreciates the fact

to working with HRMC members and others to clearly define compatibility requirements, 

and expects that EPA will realistically assess the progress being made toward those 

goals in determining whether additiona

members believe that resolution of all of these issues by the 2016

provided for by EPA will be extremely challenging but will strive to achieve that goal. 

HMRC understands the need for and sup

powertrain systems are compatible with existing heavy

Compliance and Innovative Strategies Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

Duty Hybrid Powertrain Systems and Heavy-Duty Engine On

Eaton Corporation is a member of the Hybrid Manufacturers Regulatory Collaboration 

The HMRC was formed to bring together companies involved in the heavy

hybrid vehicle industry for purposes of addressing common issues associated with 

regulations affecting hybrid vehicles. HMRC’s other current members are Allison 

., and BAE Systems Inc.

HMRC would like to express its sincere appreciation to you and your staff at EPA for 

addressing issues that have recently become apparent regarding heavy-duty hybrid 

powertrain systems and heavy-duty engine on-board diagnostic (OBD) requirements. We 

strongly believe that your actions will make it possible to avoid a serious disruption of the 

duty vehicle industry and adverse impacts on the market for such vehicles. 

This in turn will ensure the viability of heavy-duty hybrid vehicles in playing an integral 

role in allowing compliance with the Greenhouse Gas Emissions Standards and Fuel 

Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles being 

In addition, HMRC appreciates the fact that EPA has quickly shown a strong commitment 

to working with HRMC members and others to clearly define compatibility requirements, 

and expects that EPA will realistically assess the progress being made toward those 

goals in determining whether additional time is required to achieve them. HMRC 

members believe that resolution of all of these issues by the 2016-2017 model

provided for by EPA will be extremely challenging but will strive to achieve that goal. 

HMRC understands the need for and supports the goal of ensuring that heavy

powertrain systems are compatible with existing heavy-duty engine OBD requirements. 

Duty Engine On-Board 

Eaton Corporation is a member of the Hybrid Manufacturers Regulatory Collaboration 

The HMRC was formed to bring together companies involved in the heavy-duty 

hybrid vehicle industry for purposes of addressing common issues associated with 

regulations affecting hybrid vehicles. HMRC’s other current members are Allison 

HMRC would like to express its sincere appreciation to you and your staff at EPA for 

duty hybrid 

) requirements. We 

strongly believe that your actions will make it possible to avoid a serious disruption of the 

duty vehicle industry and adverse impacts on the market for such vehicles. 

hybrid vehicles in playing an integral 

role in allowing compliance with the Greenhouse Gas Emissions Standards and Fuel 

Duty Engines and Vehicles being 

that EPA has quickly shown a strong commitment 

to working with HRMC members and others to clearly define compatibility requirements, 

and expects that EPA will realistically assess the progress being made toward those 

l time is required to achieve them. HMRC 

2017 model-year as 

provided for by EPA will be extremely challenging but will strive to achieve that goal. 

ports the goal of ensuring that heavy-duty hybrid 

duty engine OBD requirements. 
Page 2 of 5 Cleophas Jackson, U.S. Environmental Protection Agency July 14, 2011 

HMRC members currently produce hybrid powertrain systems that conform to all 

mechanical/electrical interface specifications and operational specifications provided by 

heavy-duty engine manufacturers; nevertheless, there are a number of issues associated 

with ensuring compatibility with heavy-duty engine OBD requirements. Resolution of 

these issues, which are described in the attachment to this letter, will require time and the 

cooperative efforts of hybrid powertrain system manufacturers, engine manufacturers, 

heavy-duty vehicle OEMs, industry associations such as the Society of Automotive 

Engineers and the Engine Manufacturers Association, and, importantly, regulatory 

agencies. Further, HMRC believes that the failure of good faith efforts on the part of 

regulatory agencies or the affected industry to meet key deadlines necessary for 

compliance must lead to reconsideration of the timing of the compliance goal. 

In closing, HMRC would again like to express appreciation for EPA’s timely and 

responsive action to address concerns regarding OBD and heavy-duty hybrid vehicles. 

As our cooperative efforts progress, HMRC members may provide further questions 

and/or request further direction as new realizations occur as a result of the knowledge 

gained along the path of development. Finally, realizing that there may be personnel and 

other changes within regulatory agencies and industry over the timeline of this work, we 

would request that this document and its attachment be included in the Federal Register 

docket for this proceeding for use as a future reference and to help provide continuity in 

the guidance provide by the regulatory agencies. 

Best Regards, 

Ian D. McKenzie 

Chief Engineer, On-Board Diagnostics 
Page 3 of 5 Cleophas Jackson, U.S. Environmental Protection Agency July 14, 2011 

ATTACHMENT 

HMRC believes that the points summarized below are highly pertinent to the issues that 

exist with heavy-duty hybrid powertrain systems and heavy-duty engine on-board 

diagnostic (OBD) requirements. HMRC also believes that these issues must be 

considered now and in the future when assessing heavy-duty engine OBD requirements 

for engines used in combination with hybrid powertrain systems. 

1. The heavy-duty vehicle industry is non-vertically integrated and a single vehicle 

OEM or body builder may source from multiple component or system suppliers, 

who are different and independent and integrate an engine, transmission, and 

other devices, including hybrid powertrain systems. As vehicle purchasers dictate 

the “build” of a hybrid vehicle, market acceptance of hybrids requires that hybrid 

powertrain systems be compatible with a wide range of engines and other 

components. 

2. Because hybrid powertrain systems modify heavy-duty engine duty cycles in order 

to achieve reductions in fuel consumption and greenhouse gas emissions, there is 

confusion regarding how heavy-duty engine OBD requirements are applied to 

hybrid powertrain systems. 

3. Heavy-duty engine manufacturers are currently challenged by requirements to 

create OBD systems for their conventional products for the first time. Given this 

new and significant level of effort, they have not been able to provide the 

specifications that HMRC members require to ensure compatibility of hybrid 

powertrain systems with OBD compliant engines. In order to be successful in 

ensuring compatibility, HMRC members need not only the commitment of time 

and resources by engine manufacturers, but agreement from the engine 

manufactures that the OBD algorithms as well as the engine control software and 

hardware are mature and stable. It is also important that some mechanism be 

created to address the concerns of hybrid powertrain system manufacturers if 

there are future changes. 

4. OBD-compliant heavy-duty engines have only recently begun to enter the market, 

generally on engines of larger displacement and power ratings than typically 

selected for use in hybrid vehicle applications. OBD-compliant engines of the 

types that are generally used in hybrid applications have not yet been introduced 

and HMRC members do not yet have familiarity integrating hybrid powertrain 

systems with OBD-compliant versions of these engines. Time is required for 

HMRC members to obtain OBD-compliant engines and gain experience 

integrating hybrid powertrain systems with those engines in order to ensure 

compatibility with engine OBD monitoring systems 

5. Compliance with heavy-duty OBD requirements creates a new level of complexity 

in hybrid powertrain and engine integration. Presently, hybrid powertrain 

integration is accomplished with proprietary communication interfaces that are 

different for each HMRC member. Time will be required to understand what 

changes will be needed to address the integration challenges that must be 

overcome in order to ensure OBD compliance. Once that understanding has 

been achieved, additional time will be required to develop generic industry 
Page 4 of 5 Cleophas Jackson, U.S. Environmental Protection Agency July 14, 2011 

standard practices and apply those to the integration of hybrid powertrain systems 

to achieve OBD compliance. 

6. Regulatory agencies have not yet published guidance regarding the requirements 

that HRMC members will have to satisfy in order to demonstrate the compatibility 

of hybrid powertrain systems with OBD-compliant heavy-duty engines. 

Establishment of these requirements is critical to achieving the common goal of 

OBD compliance for heavy-duty hybrid vehicles and must be completed quickly. 

HMRC believes that the requirements for demonstrating compatibility need to be 

available several years prior to the OBD compliance date in order to allow 

sufficient response time for all parties involved. Significant agency resources (i.e., 

technical, engineering, and program management) will have to be rapidly made 

available to develop this guidance so that the regulatory requirements for the 

certification of engines integrated with hybrid powertrain systems can be 

articulated and communicated to engine manufacturers, HMRC members, and 

other interested parties. One example of where guidance is needed in detailing 

the exact criteria that have to be satisfied for the agency to determine that a 

hybrid powertrain system is compatible with an OBD compliant engine. In this 

case, HMRC strongly supports criteria based on engineering and technical 

analysis and strongly opposes criteria that are based on engine and/or chassis 

dynamometer testing as the latter are overly expensive and unnecessary. 

Another example where agency guidance in needed quickly is with respect to the 

requirements and criteria that will apply to all parties involved in the production of 

hybrid vehicles since significant business risk and various industry business 

functions (such as warranty requirements, service support for the end user, 

periodic field test reporting, intellectual property disclosure, to name a few) would 

likely be impacted. Again, the need for specific requirements in these areas and 

the associated cost must be carefully considered by EPA. Finally, regulatory 

agencies and the affected industry need to create an overall timeline identifying 

key deadlines by when “deliverables” such as agency guidance and industry 

standards must be finalized, so that sufficient information is exchanged at pivotal 

milestones. Without such a timeline, it is likely that there will be delays in 

achieving objectives in the critical path of achieving the goal of full OBD 

compliance in the 2016-2017 model-year timeframe. Failure of good faith efforts 

on the part of regulatory agencies or the affected industry to meet key deadlines 

on the timeline must lead to reconsideration of the timing of the compliance goal. 

7. Low sales volumes (roughly 11,000 heavy-duty hybrid powertrain systems have 

been sold nationwide over the last 11 years) limit resources available to HMRC 

members for ensuring compatibility with OBD-compliant heavy-duty engines and 

the ability to recover costs associated with demonstrating compatibility. These 

resource limits directly affect business decisions regarding continued participation 

in the hybrid powertrain market and need to be carefully considered by regulatory 

agencies in establishing compliance dates and requirements. Further, regulatory 

agencies must recognize that policies regarding emission control system warranty 

and other requirements for hybrid powertrain systems can add additional costs 

that are difficult to recover. Again, the potential for recovery of any added costs is 

a key consideration in business decisions made by HMRC members. 

8. Engine manufacturers whose primary products are engines for conventional 

vehicles face even greater resource limitations in dealing with hybrid-related OBD 

compatibility issues. Given this and low hybrid powertrain system sales volumes, 
Page 5 of 5 Cleophas Jackson, U.S. Environmental Protection Agency July 14, 2011 

engine manufacturers may just decide to prohibit the use of their products with 

hybrid powertrain systems and that decision would immediately destroy the 

industry. 

9. EPA must recognize that its demand for full OBD compliance in the 2016-2017 

model-year timeframe for engines operated with hybrid powertrain systems, as 

opposed to a later compliance date, introduces a significant cost-recovery 

obstacle for HMRC members who will have to engage in accelerated engineering 

development programs and other activities that require significant additional 

capital resources. As the hybrid industry, engine manufacturers, industry 

organizations, and regulatory agencies move forward in their efforts to achieve 

OBD compliance, the ability of companies to recover compliance costs has to be 

a key consideration if the hybrid industry is to survive.