NHTSA is debating whether to raise the fuel efficiency standards beyond what they proposed in April. The public has 30 days to comment on NHTSA’s study though it appears the agency won’t dramatically increase requirements further. Automakers have sharply criticized NHTSA’s proposal and its draft environmental statement. In August, the Alliance of Automobile Manufacturers, the trade association that represents Detroit’s Big Three automakers, Toyota Motor Corp., Daimler AG, and six other auto companies, called it at different points “illogical,” “wholly inconsistent” and that the agency vastly overstated the benefits improving fuel economy. Automakers argued the agency “improperly exaggerates the environmental benefits that its discretionary choices appear to achieve.” Dave McCurdy, the alliance’s CEO, said Friday the companies “share with all Americans concerns about energy security and climate change,” adding that “greenhouse gas emissions from automobiles must be built on a single, strong national standard.” The environmental impact statement said the proposed fuel economy increases could reduce gasoline usage by 19.5 billion gallons through 2020 and reduce carbon dioxide emissions by 185 million metric tons through 2100. But its effect on the world by 2100 would be small, reducing carbon dioxide emissions by 2.6 parts per million, lowering the predicted sea level rise by up to 0.11 centimeters and reducing the predicted increase in global mean surface temperature by up to 0.013 degrees celsius. NHTSA has been working to finalize the landmark increase in fuel efficiency regulations, which will give direction to automakers and implement the first passenger car fuel efficiency increases in more than two decades. The agency has estimated it will cost automakers $47 billion to comply with the regulations but that too has been a sticking point. Automakers say the cost would be much higher. “There is evidence that manufacturers cannot pass on to buyers the full costs of complying with higher CAFE standards,” NHTSA said. Still, environmentalists argue NHTSA could force automakers to do much more to improve fuel efficiency. Acting NHTSA Administrator David Kelly said Friday “our goal of setting ambitious but achievable fuel economy standards remains the same.”