by Josie Garthwaite
National Geographic
August 17, 2012
In the United States, the Obama administration is soon to set mileage standards that will force automakers to double the average efficiency of their fleets to 54.5 miles per gallon by 2025. The European Union is driving beyond that goal, enacting carbon emissions limits that will require new car fleets to achieve 57.4 mpg by 2020. Canada, Japan, China, and South Korea also ramp up standards starting in 2015.