Lotus Engineering, known worldwide for its expertise in mass minimization, has just completed a new study aimed at identifying potential weight reduction opportunities in vehicles intended for production in 2017 and 2020. According to the findings of this technical paper, Lotus says it would be possible to reduce mass (not including the powertrain) by the targeted 20 percent on the former "Low Development" package and by a 40-percent 2020 bogey on the "High Development" variant with minimal additional costs. Even under the latter, more demanding regimen, the price premium on a component-only basis came out to only three percent above the existing level while the former formula actually netted a two-percent reduction.
Lotus did point out that various indirect costs as well as structural and impact analyses were beyond the scope of this particular study and could ultimately impact the bottom line. However, it was able to call upon its long-term experience and expertise in automotive applications of light alloys, composite materials, and bonded structures to ensure the efforts had serious real-world implications. Equally important, major cuts in curb weight will yield significant increases in overall fuel efficiency and corresponding reductions in greenhouse gas emissions.
Slimming Down Synergistically
Lotus Engineering began its investigation by selecting a 2009 Toyota Venza as the baseline target. However, it says the materials, concepts and methodologies applied to reducing mass in this package are equally applicable to other vehicle segments. To ensure parity, the two future replacement models retained all of the existing exterior/interior dimensions and were created to offer the same level of comfort, structural/safety and perceived quality found in the production Venza.
Darren Somerset, chief executive officer of Lotus Engineering Incorporated, Lotus' North American engineering division which led the study, outlined the methodology. "A highly efficient total vehicle system level architecture was achieved by developing well integrated sub-systems and components, innovative use of materials and process and the application of advanced analytical techniques. Lotus Engineering is at the forefront of the automotive industry's drive for the reduction in CO2 and other greenhouse gas emissions and this study showcases Lotus Engineering's expertise and outlines a clear roadmap to cost effective mass efficient vehicle technologies."
In the case of the 2017 "Low Development" Venza variant, the team managed to pull 21 percent of the weight (611 pounds) out of the package while using existing industry-leading technologies. In the case of the more ambitious 2020 exercise, their efforts ended up trimming 38 percent of the mass (1,093 pounds). The biggest individual weight losses in the 2020 High Development vehicle were realized in the area of its suspension/chassis (43 percent), unit body (42 percent), fenders/closures (41 percent), interior (39 percent) and electrical (36 percent) systems.
While the reduction in powertrain mass was not figured directly into the equation for either architecture, the Lotus design brief anticipates replacing the existing four-cylinder with either a smaller, lighter 1.5-liter turbocharged/direct-injected three-cylinder version of its super-efficient SABRE gasoline engine or an advanced version of the dual-mode hybrid powered by a lithium-ion battery. The latter drivetrain package would cut the relative weight by 31 percent (99 pounds) compared to the 2009 Venza.
Driving Towards a Cleaner Tomorrow
The ultimate cost-to-benefit implications of this new Lotus study can best be understood in terms of estimates made by the U.S. Department of Energy. According to DOE stats, cutting total vehicle mass by 33 percent including powertrain, as demonstrated on the 2020 passenger car model created by Lotus, would result in a 23 percent reduction in fuel consumption and an equivalent cut in greenhouse gas emissions.
Dr. Robert Hentschel, director of Lotus Engineering summed it up by saying: "Lighter vehicles are cleaner and more efficient. That philosophy has always been core to Lotus' approach to vehicle engineering and is now more relevant than ever. Lightweight Architectures and Efficient Performance are just two of our core competencies and we are delighted to have completed this study with input from the National Highway Traffic Safety Administration and the U.S. Environmental Protection Agency to provide direction for future CO2 reductions. We believe that this approach will be commonplace in the industry for the future design of vehicles."