Stojkovski argued that automakers will need to add a wide variety of new technologies to get to 54.5mpg, including improvements to engines, transmissions, and tires. Engineers will also need to cut vehicle weight and drag, while simultaneously electrifying certain models.
Consumer advocates said the 54.5mpg number is not as daunting as it seems, however. That figure is not the same as the EPA sticker number on every vehicle, since the two are calculated differently, Gillis said. He pointed out that the 54.5mpg number translates to 45mpg on an EPA sticker. "So when you think of the fact that the goal in EPA numbers is 45, it becomes clear that it is very achievable," he said.
Engineering consultants contended that no matter how it's calculated, the new rule still calls for a 70 percent increase in fuel efficiency, which will be costly.
Consultants also worried about the rule's effect on the market for new vehicles. "When you reach 35, 40, and 50 miles per gallon, the cost to achieve it gets too high," David Cole, chairman emeritus of The Center for Automotive Research (CAR) and a former professor of automotive engineering the University of Michigan, said in an interview. "And the value returned to the customer gets to be less and less. The risk is that people will say, 'Why should I buy a new car? I'll just keep the old one. It's a better business decision.' "
Stokovski agreed that the higher initial cost of vehicles will significantly affect the market. The technology's extra cost might make it more difficult for some consumers to get credit in a tight market. "A lot of new technology will be needed," Stojkovski said. "And you don't get a 70 percent increase in fuel economy for free."