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Advanced Technologies for Light-Duty Vehicles |
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A fundamental concern in projecting the future attributes of light-duty vehicles—passenger cars, sport utility vehicles, pickup trucks, and minivans— is how to represent technological change and the market forces that drive it. There is always considerable uncertainty about the evolution of existing technologies, what new technologies might emerge, and how consumer preferences might influence the direction of change. Most of the new and emerging technologies expected to affect the performance and fuel use of light-duty vehicles over the next 25 years are represented in NEMS; however, the potential emergence of new, unforeseen technologies makes it impossible to address all the technology options that could come into play. The previous section of “Issues in Focus” discussed several potential technologies that currently are not represented in NEMS. This section discusses some of the key technologies represented in NEMS that are expected to be implemented in light-duty vehicles over the next 25 years. The NEMS Transportation Module represents technologies for light-duty vehicles that allow them to comply with current standards for safety, emissions, and fuel economy or may improve their efficiency and/or performance, based on expected consumer demand for those attributes. Technologies that can improve vehicle efficiency take two forms: those that represent incremental improvements to or advancements in the various components of conventional power trains, and those that represent significant changes in power train design. Advanced technologies used in vehicles with new power train designs include, primarily, electric power propulsion systems in hybrid, fuel cell, and battery-powered vehicles. Historically, the development of new technologies for light-duty vehicles has been driven by the challenge of meeting increased demand for larger, quieter, more powerful vehicles while complying with emissions, safety, and fuel economy standards. The auto industry has met those challenges and, through technological innovation, delivered larger, more powerful vehicles with improved fuel economy. In 1980, the average new car weighed 3,101 pounds, had 100 horsepower, and averaged 24.3 miles per gallon. In 2004, the average new car weighed 3,454 pounds (an 11-percent increase), had 181 horsepower (an 81-percent increase), and averaged 29.3 miles per gallon (a 21-percent increase). Improvements in new light trucks (including sport utility vehicles) from 1980 to 2004 have been even more profound: their average weight has increased by 20 percent to 4,649 pounds, their horsepower has increased by 91 percent to 231, and their average fuel economy has increased by 16 percent to 21.5 miles per gallon [47]. The majority of improvements in horsepower and fuel economy for new light-duty vehicles have resulted from changes in conventional vehicle components, including fuel delivery systems, valve train design, aerodynamics, and transmissions. In 1980, almost all new light-duty vehicles employed carburetors for fuel delivery; in 2004, all new light-duty vehicles used port fuel injection systems, which improve engine efficiency through very precise electronic control of fuel delivery. Advances have also been made in valve train design, improving efficiency by reducing engine pumping losses. In 1980, all engine designs used two valves per cylinder; in 2004, engines with four valves per cylinder were installed in 74 percent of new cars and 43 percent of new light trucks. Increases in light-duty vehicle horsepower and fuel economy are projected to continue in the AEO2006 cases at rates similar to their historical rates, while vehicle weight remains relatively constant. For example, between 2005 and 2030 new car horsepower increases by 19 percent, to 215, in the reference case, while fuel economy increases by 15 percent to 33.8 miles per gallon; and the horsepower of new light trucks increases by 14 percent, to 264, and fuel economy increases by 23 percent to 26.4 miles per gallon, while their weight increases by 4 percent to 4,828 pounds. Most of the improvements result from innovations in conventional vehicle components. To project potential improvement in new light-duty vehicle fuel economy, 63 conventional technologies are represented in the Transportation Module. The technologies are grouped into six vehicle system categories: engine, transmission, accessory load, body, drive train, and independent (related to safety and emissions). Table 13 summarizes the technologies expected to have significant impacts over the projection period, the expected range of efficiency improvements, and initial costs. Engineering relationships among the technologies are also modeled in the Transportation Module. The engineering relationships account for: (1) co-relationships, where the existence of one technology is required for the existence of another; (2) synergistic effects, reflecting the combined efficiency impact of two or more technologies; (3) superseding relationships, which remove replaced technologies; and (4) mandatory technologies, needed to meet safety and emissions regulations. In addition to the engineering relationships, reductions in technology cost are captured as unit production increases or cumulative production reaches a design cycle threshold. Technologies expected to show the greatest increase in market penetration, and thus the greatest impact on new car and light truck efficiency, include lightweight materials, improved aerodynamics, engine friction reduction, improved pumps, and low rolling resistance tires (Figures 17 and 18). These technologies represent the most cost-effective options for improving fuel economy while meeting consumer expectations for vehicle performance and comfort. The weight of new cars remains relatively constant as a result of increased market penetration of high-strength low-alloy steel (63 percent by 2030), aluminum castings (24 percent by 2030), and aluminum bodies and closures (12 percent by 2030). Variable valve timing and lift and camless valve actuation are also expected to have a significant impact on new car efficiency, with installations increasing to approximately 30 percent and 4 percent, respectively, in 2030. The use of unit body construction in new light trucks increases from 23 percent in 2004 to 36 percent in 2030 as more sport utility vehicles and pickup trucks are developed from car-based platforms. The efficiency of new light-duty vehicles also improves with increased market penetration of hybrid and diesel vehicles. Depending on the make and model, the incremental cost of a power-assisted hybrid vehicle (a “full hybrid”), currently estimated at $3,000 to $10,000, decreases to between $1,500 and $5,400 in 2030 [48]. As a result, the penetration of hybrid vehicles increases from 0.5 percent of new light-duty vehicle sales in 2004 to 9.0 percent in 2030. Market penetration of diesel vehicles increases from about 2 percent in 2004 to more than 8 percent in 2030. Battery and fuel cell powered vehicles also penetrate the light-duty vehicle market as a result of legislative mandates, but with very high vehicle costs, limited driving range, and the lack of a refueling infrastructure, they account for only 0.1 percent of new vehicle sales in 2030.
Contact: John Maples |
