Assessment of Technologies for Improving Light-Duty Vehicle Fuel Economy—2025-2035 (2021) / Chapter Skim
Currently Skimming:
2 Fuel Economy, Greenhouse Gas Emissions, and Vehicle Efficiency Background
2 Fuel Economy, Greenhouse Gas Emissions, and Vehicle Efficiency Background
Pages 20-30
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 20... ...
2.1 TECHNOLOGY PRINCIPLES AFFECTING VEHICLE EFFICIENCY This report is tasked with informing the National Highway Traffic Safety Administration (NHTSA) , Congress, and the public on fuel economy technology potential relevant in 2025–2035.
|
From page 21... ...
Optimizing vehicle shape by streamlining and with active and passive design add-ons can reduce the drag coefficient, and hence the energy losses in aerodynamic drag. 2.1.3 Rolling Resistance In addition to aerodynamic drag and inertial force owing to mass, tire rolling resistance is one of the many forces that must be overcome in order for a vehicle to move.
|
From page 22... ...
2.2 FUEL CONSUMPTION, GHG EMISSIONS, AND ENERGY USE As introduced in Chapter 1, vehicle energy consumption, fuel consumption, and GHG emissions are related metrics. At base is vehicle energy use.
|
From page 23... ...
. TABLE 2.1 Total Onboard Energy Flows as Estimated for ICEVs, HEVs, and BEVs ICEV HEV BEV Energy Flow % Energy Loss % Energy Loss % Energy Loss Engine losses 68–72 65–69 N/A Battery charging and electric drive system losses N/A N/A 20 Parasitic losses 4–6 4–6 N/A Drivetrain losses 5–6 3–5 N/A Auxiliary electrical losses 0–2 0–3 0–4 Idle losses 3 0 0 Regenerative braking recovery N/A + 5–9 + 17 Power to wheels + 16–25 + 24–38 + 86–90 NOTE: Some percentages may not add to 100% owing to rounding and variable ranges.
|
From page 24... ...
. Fuel economy standards, achieved fuel economy, and resulting vehicle energy efficiency improvements over time are shown in Figure 2.2.
|
From page 25... ...
• Average Fuel Economy Standards for Light Trucks The CAA gives the EPA the authority to regulate air pollutants harmful to MY 2008–2011 humans. Originally passed in 1970, the CAA has been amended several • Light-Duty Vehicle Greenhouse Gas Emission times since to include newly recognized pollutants and was the focus of Standards and Corporate Average Fuel Economy a 2007 Supreme Court case establishing if GHGs fall under the CAA Standards; Final Rule (2010, MY 2012–2016)
|
From page 26... ...
One notable example is that reducing the mass of materials on the vehicle can present improvements in fuel economy; however, historically, there has been concern about the passenger safety implications of reducing vehicle mass, or "lightweighting." The precise relationship between vehicle mass and safety risk is complex, however, with the potential for vehicle material selections to be made that improve fuel economy through mass reductions but without necessarily decreasing safety. Recent technological developments such as advanced driver assistance systems can enhance both safety and fuel economy through assisting drivers with breaking, acceleration, and/or steering (NHTSA/EPA, 2020)
|
From page 27... ...
FUEL ECONOMY, GREENHOUSE GAS EMISSIONS, AND VEHICLE EFFICIENCY BACKGROUND 27 FIGURE 2.3 Implementation of fuel injection, lockup, multivalve engines, variable valve timing, advanced transmissions, gasoline direct injection, and turbocharging by major manufacturer, showing the time it takes for a technology to be implemented in a large percentage of a manufacturer's fleet, and the variability in implementation of technologies across different manufacturers.
|
From page 28... ...
2.3.3.3 Vehicle Efficiency Information and Labeling EPA fuel economy labeling has been on vehicles since 1974, with the most recent label design (2012) providing ratings on vehicle smog and GHG emissions and estimates of how much the consumer will save on fuel in the next 5-year period (compared with an average new vehicle)
|
From page 29... ...
Off-cycle credits can be awarded to technologies that deliver real-world fuel economy benefits or decrease emissions but are insufficiently counted on the official test cycle. Other driving conditions excluded from the tests that may reduce fuel economy, such as wind, low tire pressure, rough roads, hills, snow, or ice, are accounted for in the fuel economy labels by decreasing the measured fuel economy by an adjustment factor; however, this adjustment is not applied to CAFE compliance measurements.
|
From page 30... ...
2012. "2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy Standards." Federal Register 77(99)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.