In mid-2012, Barack Obama announced a new and historic fuel efficiency standard of 54.4 mpg by 2025. Certainly, the global warming alarmists were delighted.
Now, just 4 years later, that new target is falling apart. Not, because the technology isn't there to hit those mileage goals. It is. But, Americans are responding to cheap gasoline prices and not buying either hybrid or electric cars. Worse yet, instead of fuel efficient cars, they're opting for gas guzzling SUV's and trucks.
But, in an irony of ironies, the quest for more fuel efficiency in cars to meet the still-mandated 2025 standards, the industry is moving towards engines with Direct Fuel Injection engines that are now proven to output more black carbon than their predecessors. This according to the American Chemical Society. Thus, while the nation may see higher fuel efficiency in their automobiles, the environment may actually suffer more carbon pollution. It appears that you can't have both. The President may have made a poor decision on fuel efficiency that would do more harm than good; but then, he won't be in office when that hammer falls, and that fact becomes widespread knowledge.
Obama Administration Finalizes Historic 54.5 MPG Fuel Efficiency: https://www.whitehouse.gov/the-press-office/2012/08/28/obama-administration-finalizes-historic-545-mpg-fuel-efficiency-standard
CAFE standards won't hit 54.5 by 2025, regulators say: http://autoweek.com/article/car-news/buyer-appetite-takes-545-mpg-target-table-us-regulators-say
As electric cars stall, a move to greener trucks and buses: GreenBiz: https://www.greenbiz.com/article/electric-cars-stall-move-greener-trucks-and-buses
Could more fuel-efficient engines lead to more global warming?: https://wattsupwiththat.com/2016/07/13/could-more-fuel-efficient-engines-lead-to-more-global-warming/