USCAR Works to Get Clean Diesel Technologies


SOUTHFIELD, Mich., Oct. 15, 2009 – As diesel engines gain momentum as one cost-effective means to improve fuel efficiency, Chrysler, Ford and General Motors are working collaboratively through the United States Council for Automotive Research LLC (USCAR) to adapt and develop selective catalytic reduction (SCR) technologies that will help bring more clean-diesel technologies to the U.S. and global markets.

Formed in 2005, the USCAR Selective Catalytic Reduction Working Group has developed some of the key peripheral components and processes required to integrate SCR into future cars and light-duty trucks. These include standardized fluid level sensors and warning systems and the standardization of SCR components, fluids and the SCR refilling process.

Specifically, the USCAR group established the generic name and chemical properties of “Diesel Exhaust Fluid” (DEF) for the 32.5 percent urea/purified water reductant used in SCR systems, endorsed a North American symbol for DEF, and in the process, published six whitepapers and filed patent applications for DEF filler/cap specifications. This includes a DEF filler design with reduced internal diameter that prevents a diesel fuel nozzle from being inserted into the DEF inlet to prevent the accidental dispensing of diesel fuel into the DEF tank.

Patent applications, filed in the U.S. and Europe, specify the unique design of a self-stowing tether for the filler cap to ensure the unique blue cap remains attached and identifies the DEF fluid tank.

“The U.S. automakers are key enablers of SCR technologies in the United States,” said Michael Luckham, USCAR SCR Working Group lead representative and engineering group manager, diesel aftertreatment at General Motors. “As such, our work is helping shape the discussion in defining key aspects of SCR utilization including standards for fluids, symbols and terminology, and engineering guidelines.

“SCR appears to be the most effective NOx reduction technology that is mature enough to enter production. Compared to other technologies, SCR provides better fuel efficiency and a reduction in the use of precious materials.”

Along with defining industry standards and developing the peripheral technologies, a main focus of the SCR Working Group has been to ensure that the DEF fluid level warning and refilling system functions reliably for emissions compliance.

The systems must be “fool-proof” to ensure only approved diesel exhaust fluid is dispensed into the correct tank. The low-fluid warning systems must also inhibit drivers from operating a vehicle without the fluid injection system fully functional.

Developing the low-fluid warning system specifications was essential to ensuring EPA emissions requirements would be met once the SCR systems enter into production.

“We shared our research and information with the EPA and many other organizations to ensure the specifications and designs met their requirements,” said Zafar Shaikh, chair of the USCAR SCR Working Group and technical leader at Ford’s powertrain research group. “I think that’s important because all parties realize that diesel systems are a vital part of the future transportation mix.”

A second-generation SCR working group is now underway to develop common test procedures for SCR system components, along with evaluating future NOx reduction technologies.


Founded in 1992, USCAR is the collaborative automotive technology organization for Chrysler Group LLC, Ford Motor Company and General Motors Company. The goal of USCAR is to further strengthen the technology base of the domestic auto industry through cooperative research and development. For more information, visit USCAR’s Web site at

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