From the December 2015 issue
The EPA and carmakers used to square off like two grunting NFL squads. The EPA fights to curb energy consumption and reduce air pollution, while carmakers want to score customers, whose wish lists only occasionally include high mpg ratings. But four and a half years ago, after huddling with the 13 largest manufacturers, the UAW, and the state of California, President Obama blew the whistle on this old government-industry rivalry. Now these former foes have a common goal: a Corporate Average Fuel Economy (CAFE) target of 54.5 mpg by the 2025 model year. According to the EPA, reaching it will save consumers more than $1.7 trillion in fuel costs while curbing greenhouse-gas emissions by 6 billion metric tons throughout the life of vehicles produced from 2012 to 2025.
After the Supreme Court granted the EPA the authority to regulate greenhouse-gas emissions last year, the emphasis shifted from mpg to grams of CO2 produced per mile of driving. Backed by the Intergovernmental Panel on Climate Change, the EPA figures that burning one gallon of gas emits 8887 grams of CO2. So 54.5 mpg means 163 grams CO2/mile. Manufacturers are spending billions on lighter, more-efficient vehicles to get there. Meanwhile, the EPA is recognizing creative ways to reduce vehicles’ environmental impact. The most interesting of these is called Off-Cycle Credits, a roster of ways to chip away at CO2 emissions that may not be reflected in the tests used to determine CAFE mpg figures. Companies employing these technologies earn credits without additional testing. Truck credits are higher because they burn more fuel and produce more emissions.
Currently Eligible Technologies
Credit Check
Grams-per-Mile Credit, Car/Truck
Reduced cabin thermal loads: up to 3.0/4.3
Solar-reflective glass and paint are very effective at lowering interior temperatures and reducing HVAC system loads.
Battery charging with a 75-watt solar panel: 3.3/3.3
Engine stop-start with cabin-heater operation: 2.5/4.4
Toyota currently uses a system that stores heat in an insulated vessel for use in cold climates, to be released when the engine is shut down, which winds up saving fuel.
Engine stop-start without cabin-heater operation: 1.5/2.9
This nets fewer credits because drivers are more likely to disable stop-start if occupant comfort suffers.
Active engine warm-up: 1.5/3.2
Preheating engine coolant significantly trims consumption and emissions after a cold start.
Active transmission warm-up: 1.5/3.2
Warming powertrain fluids diminishes friction losses and smooths upshifts. Some Ram trucks already use this technology.
Waste-exhaust heat recovery, 100 watts: 0.7/0.7
Thermoelectric generators convert waste-combustion heat to electricity for powering a propulsion motor or reducing the alternator’s load. No manufacturer has put such a system into production yet.
High-efficiency lighting, 100-watt savings: 1.0/1.0
LED lighting consumes half the energy of HID lamps and only a quarter as much as halogen lights providing the same illumination.
Active aerodynamics, 3-percent drag reduction: 0.6/1.0
Small Savings, Big Gain
Manufacturers can also nominate new methods for consideration. Last year, Mercedes-Benz applied for a 9.1-grams-per-mile credit for its stop-start system in cars and 17.1-grams-per-mile credit for its trucks. The EPA granted credits of 3.7 and 3.6 grams per mile for 2012–2016 model years. GM applied for and received a 1.1-grams-per-mile credit for cars equipped with more-efficient air-conditioning compressors.
Off-cycle credits are limited to a maximum of 10 grams of CO2 per mile per vehicle (or 3 mpg). That may seem like small potatoes, but it tallies up to millions of dollars and tons of CO2 when multiplied by the number of vehicles produced and each vehicle’s 200,000-or-so-mile service life.
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