Munro warned that smaller, lighter vehicles could also compromise crashworthiness. "Cars are not going to have the ability to perform in a crash the way they do now," he said. "Today's cars are about as good as we'll ever see. But when you change the materials and make the vehicles smaller, something has to give."
Crashworthiness would not be affected if the auto industry moved to a heavy diet of hybrids, plug-in hybrids, and pure electric vehicles, Munro said. Vehicles such as the Chevy Volt and Nissan Leaf already offer superior crash safety, while already earning miles-per-gallon-equivalent ratings in excess of 90 mpg-e. Still, pure electrics and plug-in hybrids would raise costs for consumers, he said.
Automakers have, of course, traditionally resisted all government-led efforts to boost fuel economy, ever since CAFE regulations were first introduced in 1978. During that time, standards have risen from 18.0 mpg for passenger cars in 1978 to 35.5 mpg for combined (trucks and cars) in 2016. The next step is the current proposal (still being debated) of 54.5 mpg by 2025, which calls for the biggest fuel efficiency boost to date.
Munro contends that unforeseen technology developments could have a profound effect on the industry's ultimate ability to reach the 2025 targets. Improvements in EV batteries or hydrogen fuel cells are being worked on, and unexpected innovations in other areas can't be ruled out, he said. "There are lots of things that could happen," he said. "And if one of them suddenly does, then you could have a game changer."