Everyone appreciates how higher fuel efficiency is important
for controlling oil use and greenhouse gas (GHG) emissions. Although efficiency
can be given a big boost by making a vehicle all-electric, plug-in cars have
limitations as well as high costs. And so a key question is this: how much can we
improve the fuel economy of "grid-free" automobiles that still use only
gasoline?
Most technologies can progress quite a lot given sufficient
time, but policymakers concerned about climate want to cut GHG emissions substantially by mid-century. Because it takes roughly 15 years to replace the on-road stock
of cars and light trucks, the relevant question becomes that of how much more efficient
new vehicles could be by 2035.
An answer is provided in a recent report, A Fuel Efficiency Horizon
for U.S. Automobiles. This study examines how far auto efficiency can be
taken if it is pursued with determination, using technology and design options that
offer a "revolution by evolution."
Quite a lot of progress -- as much as a tripling of new fleet average fuel economy -- can be made through ongoing refinements to vehicles that
still rely on internal combustion engines as their sole and prime mover. Costs
are involved, but much less than the costs of electric and
other alternatively fueled vehicles (AFVs), which face infrastructure
barriers and other market challenges.
