Deciphering the new vocabulary of the green car movement can sometimes be a real head scratcher. To alleviate as much confusion as possible, we would like to present our readers with a list of common acronyms and what they mean, with plenty of links for more information. If you have some TLAs (that's three-letter acronyms) that you'd like us to add to our glossary, just let us know in the comments.

Find the list after the jump.

Photo by thrig. Licensed under Creative Commons license 2.0.


B5 (also: B20, B99) – Petroleum diesel fuel mixed with biodiesel. The number is the percentage of biodiesel in the liquid, so B5 is 95 percent petroleum and five percent biodiesel.

BEV – Battery electric vehicle. That is, an electric vehicle without a range extender, like an engine or a hydrogen fuel cell, of any type.

CAFE – Corporate Average Fuel Economy standards. A system used in the United States to define the mileage requirements of new vehicles. More details here.

CARB – The California Air Resources Board. It's mission is, "To promote and protect public health, welfare and ecological resources through the effective and efficient reduction of air pollutants while recognizing and considering the effects on the economy of the state."

CVT – Continuously variable transmission. A type of transmission with an effectively infinite number of gear ratios that provides improved fuel economy because the engine can run at its most efficient revolutions per minute independent of vehicle speed. Wiki here.

DCT – Dual-clutch transmission. A single housing that contains two separate transmissions and clutches. Can improve fuel economy. Wiki here and a video showing how it works is available here.

DI – Direct injection. A type of fuel injection in a gasoline engine that uses high pressure to inject the fuel directly into the combustion chamber. This can provide better fuel efficiency and lowered emissions in some situations. Wiki here.

DSG – Direct shift gearbox. Another name for dual-clutch transmission.

E85 (also: E10, E15) – Petroleum gasoline mixed with ethanol. The number is the percentage of ethanol in the liquid, so E85 is 15 percent petroleum and 85 percent ethanol.

EDTAElectric Drive Transportation Association. Puts on the annual EDTA conference and is self-described as "dedicated to advancing electric drive as a core technology on the road to sustainable mobility. As an advocate for the adoption of electric drive technologies, EDTA serves as the unified voice for the industry and is the primary source of information and education related to electric drive. Our membership includes a diverse representation of vehicle and equipment manufacturers, energy providers, component suppliers and end users."

ER-EV – Extended range electric vehicle. A vehicle that is driven by an electric powertrain but includes a powerplant that can recharge the batteries on the go, through a fuel cell or a liquid-fueled engine. This is GM's preferred term for the Chevy Volt's powertrain.

GTDI – Gasoline turbocharged direct-injection. Gasoline-powere engines that use higher compression ratios and inject fuel just before ignition. Ford's EcoBoost engines use GTDI. Explained in full here and here.

H2 – Hydrogen.

HCCI – Homogeneous charge compression ignition. A gasoline engine that uses high temperatures generated by compressing the intake stream to ignite the fuel. Explained here.

HHO – Hydrogen-on-demand. A way to make hydrogen in a vehicle and use it in the engine. Not commonly accepted as an effective fuel-saving technology.

ICE – Internal combustion engine.

Li-ion – Lithium-ion. A type of battery chemistry commonly used in advanced automobile batteries to provide more power with less weight. Wiki here.

MPGe – Miles per gallon equivalent. A way to calculate the longstanding miles per gallon rating used with liquid fuel-powered vehicles in a vehicle where some of the energy comes from another source, like the electric grid. See more here.

NEV – Neighborhood electric vehicle. Low-speed electric cars that may or may not look like golf carts. Explained in detail here.

NiMH – Nickel-metal hydride. A type of battery chemistry that is used in most of the hybrid vehicles on the road today. Wiki here.

PHEV – Plug in hybrid vehicle. A vehicle with two power sources, one of which is a battery that draws power from an outlet.

PZEV – Partial zero emission vehicle. One of the categories defined by the California Air Resources Board for emissions standards. Wiki here.

SAE – This acronym, which used to stand for the Society of Automotive Engineers, is now just the name of that group and related organizations. Official page here.

SULEV – Super ultra low emission vehicle. One of the categories defined by the California Air Resources Board for emissions standards. Specifics listed here and in this PDF.

SVO – Straight vegetable oil. Liquid fuel that can be used in diesel engines with some modifications. More details here and here.

TDI – Turbocharged direct injection. A name for the modern diesel engines from the Volkswagen group. Wiki here.

TSI – Turbo stratified injection. An engine that uses direct injection with a turbocharger (and sometimes a supercharger) to get more power from the same amount of fuel. More here.

ULEV – Ultra low emission vehicle. One of the categories defined by the California Air Resources Board for emissions standards. Specifics listed here and in this PDF..

VMT – Vehicle miles traveled. The number of miles that all vehicles in a national fleet travel in a given year. More here.

VVT – Variable valve timing. A system that allows the engine computer to change the lift, duration or timing of the intake and/or exhaust valves while in operation. Wiki here.

WVO – Waste vegetable oil. Similar to straight vegetable oil, but describes oil that has been used at least once for another application (e.g., cooking).

ZEV – Zero emission vehicle. One of the categories defined by the California Air Resources Board for emissions standards. Details available here.