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.