Cleaner Cars A to Z
About 8.5 million barrels of oil are used each day to fuel America’s love affair with driving. In addition to the impact on our wallets, cars and light trucks account for more than 20 percent of the United States’ total annual global warming emissions.
Driving a cleaner car can go a long way toward addressing these problems, but the “alphabet soup” of high-tech terminology can be confusing. Below, we demystify some of the most common acronyms you might come across when car shopping:
Vehicle Types
HEVs (hybrid-electric vehicles) combine an internal combustion engine with a battery-powered electric motor to get higher fuel economy (upward of 500 miles per tank) with fewer global warming emissions. However, as the UCS Hybrid Center explains, not all HEVs are created equal (see the Related Resources).
PHEVs (plug-in hybrid-electric vehicles) have bigger battery packs than HEVs, and are charged via a household wall outlet or public charging station. PHEVs can, depending on their design, drive 15 to 50 miles using little to no gasoline. PHEVs, as well as BEVs and FCEVs (see below), deliver their greatest emissions reductions when the electricity or hydrogen used to power the vehicles comes from renewable energy sources instead of fossil fuels.
BEVs (battery electric vehicles) rely solely on a battery pack to power the electric motor. Most of today’s BEVs can travel 60 to 100 miles on a full charge; a few go even farther. Like PHEVs, they are charged on the electric grid.
FCEVs (fuel cell electric vehicles), like BEVs, have no gasoline engine, but the electric motor is powered by fuel cells that combine hydrogen, from an onboard tank, with oxygen from the air to produce electricity (and water—the only exhaust waste produced). Most hydrogen refueling stations in the United States are in Southern California.
FFVs (flex-fuel vehicles) can run on gasoline, E85 (a gasoline blend with 85 percent ethanol), or any combination of the two. Ethanol generates either more or less global warming pollution than gasoline depending on the feedstock used (e.g., corn, switchgrass) and production process. E85 fueling stations are not widespread (see the Related Resources for fueling locations).
NGVs (natural gas vehicles) burn natural gas in an internal combustion engine. An NGV generates less global warming pollution than a comparable gasoline vehicle, but not necessarily less than a similar hybrid or EV. There is only one natural gas passenger vehicle (made by Honda) on the market today. See the Related Resources for fueling locations.
Technologies
VVT&L (variable valve timing & lift) adjusts the operation of an engine’s valves depending on speed and power demand, providing a better fuel/air mix and improved combustion for greater efficiency.
DEAC (cylinder deactivation), also called variable cylinder management, active fuel management, or multi-displacement, makes engines more efficient by shutting down some of the cylinders when extra power isn’t needed.
CVT (continuously variable transmission) is an automatic transmission with an essentially infinite number of gear ratios, enabling the engine to operate near optimal speed under all conditions.
