“Our expectations are that both [hybrids and conventional vehicles] will improve in a proportional way,” Heywood says. He adds, “Hybrid technology might progress faster because it is newer.”
The rest of the change needed, Heywood estimates, could be accomplished by bringing down average vehicle weight. Automakers might both redesign individual models—for instance, replacing heavy steel with lighter materials—and increase the proportion of smaller vehicles they offer.
Hitting the new CAFE mark is likely to depend on the continued evolution of certain technologies, such as variable valve-timing systems and turbocharged gasoline direct-injection engines, but no fundamental breakthroughs will be required, says John DeCicco, who researches transportation energy use and greenhouse gas emissions at the University of Michigan. “All the technologies we are talking about are essentially already in the marketplace in one form or another,” says DeCicco. “This is engineering we understand well.”
DeCicco’s view is that plug-in hybrids and pure plug-in electrics—for which breakthroughs are needed to bring down battery cost—will probably still be a niche market in 2025. But that won’t affect automakers’ ability to meet the CAFE standard, he argues. “You just don’t really need them.”
Ultimately, reaching the goal set forth in the CAFE standard may be realistic from a technological standpoint, but it will require reversing a trend of the past few decades: steady increases in vehicle weight and fuel consumption. “The amount of change required as we go 15 years into the future is bigger than people are mentally allowing for because things have been getting worse,” says Heywood. “It’s not only that it needs to get better. We need a shift from a getting-worse trajectory to a getting-better trajectory.”