A mix of current- and next-generation technologies will enable automakers to go from the present combined light-duty fleet average of 27.3 mpg to 54.5 mpg in 2025, according to officials with Ricardo Inc., an engineering services and consulting company that had input on the U.S. EPA’s CAFE rulemaking for MY2017-2025.
Ricardo’s technology roadmap for 2025 shows that vehicles powered by internal-combustion engines with three, four, or more cylinders will use various combinations of advanced boost systems, direct injection, and advanced valvetrains to facilitate performance and boost fuel economy, according to John Kasab, Ricardo Chief Engineer of Innovations.
“An advanced boost application could be two-stage, series-sequential turbocharging or a turbocharger-supercharger combination—depending on the transient performance requirements. For the valvetrain, Ricardo assumes cam profile switching will be typical by 2025,” Kasab told AEI.
Mark Kuhn, Ricardo Manager of Strategic Consulting, said that automakers and suppliers have not been sitting idle prior to the 2025 mandate, with several of them already in production with advanced valvetrain designs as well as turbocharging and direct-injection technologies as a companion to downsized engines.
While MY2016 marks the next light-duty vehicle fleet federal mandate milestone (35.5 mpg), the MY2025 timeline looms as a heady task for engineers.
Said Kasab: “The main challenge for meeting the MY2025 targets is developing a cost-effective, holistic solution for the complete vehicle or platform that can reduce losses in the engine, transmission, driveline, and vehicle. The cost considerations are why Ricardo sees the most interest in improving engine efficiency and in lowering vehicle mass.”
With the body, powertrain, and suspension/chassis accounting for approximately 70% of a vehicle’s mass, those systems are prime lightweight targets in the march toward 54.5 mpg, according to David Periam, Ricardo Chief Engineer of Vehicle Engineering.
“While there are a variety of means to achieve mass reduction and the solution will vary by vehicle class and manufacturer, it is likely the typical car body of 2025 will feature a multimaterial approach with increased use of aluminum and magnesium alloys and reinforced plastics along with continued use of steel in a variety of grades,” Periam predicted.
Improved aerodynamics, advanced transmissions, and electrified vehicles will also be part of the equation for improving an automaker’s light passenger vehicle fleet fuel efficiency.
“We see micro-hybrids—meaning start-stop systems—being pretty much standard by 2025. Ricardo also expects continued market share growth for charge-sustaining hybrids and for plug-in hybrids over the next decade,” said Kasab, adding “the market share will likely reach 10-15% for electric-hybrids.”
Engineering ingenuity is the final key to reaching the 2025 mpg mandate. “The challenge is that there is not one simple fix to reach the mpg target. It will require innovation with all of the vehicle systems. And that means clever engineering will be needed to bring it all together to meet the regulatory and manufacturing requirements at an affordable cost,” Kasab said.
Ricardo engineers assisted the EPA in its 54.5 mpg decision-making via a contract with SRA International from 2009 to 2011.
“Ricardo worked with the EPA and their advisory committee to develop a technology roadmap and define a future design space of possible configurations—ranging from compact car to full-size pickup, six engine types, four driveline options, and a number of other variables. We also evaluated the design space to allow the EPA and others the ability to access—via a dedicated EPA website—the benefits of different vehicle configurations,” explained Kasab.