According to logic (which some might say is tortured or shaped somewhat like a pretzel), safety features like automatic braking and lane-departure systems help prevent accidents. And while those accidents aren't always as dramatic as the cinematic scene described above, they do bottle up the roads and force more people to idle in traffic jams, increasing greenhouse-gas emissions as a result.
In this case, making the argument Alliance of Automobile Manufacturers, which represents a number of major automakers, including General Motors, Ford and Toyota. That group, which is charged with boosting their light-duty vehicles' collective fuel economy to a Corporate Average Fuel Economy (CAFE) of 54.5 miles per gallon (which is equal to about 40 mpg in real-world figures), wants to get some fuel-economy credits for their safety features. New cars sold today average about 25 mpg on the EPA sticker. While the federal government has so far said no dice, UC Riverside estimates that accident-avoidance features and other traffic-flow advancements can help cut down vehicle emissions by as much as 30 percent.