Hybrid Terminology
Is the Volt an electric vehicle or a hybrid?

Is the Chevrolet Volt an electric vehicle or a hybrid? There has been some controversy here. Chevy likes to call it an Extended Range Electric Vehicle (EREV). It has a gas engine that can help drive it, so it is a hybrid. But is it valid to also call it an electric vehicle?

Depiction of Serial vs. Parallel

Part of the distinction has to do with whether the vehicle is a "serial" hybrid or a "parallel" hybrid. Early hybrids, and most hybrids that are on the road today, are parallel hybrids. In a parallel hybrid, both the gas engine and the electric drive systems work together to achieve improved efficiency over regular gas powered cars. In a serial hybrid, the car is driven entirely by the electric drive systems, but a gas engine serves as a backup generator to charge the batteries when battery charge is low. Thus, a serial hybrid can be thought of as an electric vehicle that has a gas generator on board to provided extended range.

Part of the Volt controversy that sometimes flares up is because the final design of the "Voltec" system is actually that of a serial/parallel hybrid. Most of the time, the Volt operates in serial mode, but above a certain speed (around 65 mph, according to what info I can find), it begins to operate in parallel mode.

It's true that regular parallel hybrids sometimes run on the batteries alone (when coasting down a hill, or sitting at a stop light, for example). However, the system is still designed as a collaborative system. The difference is subtle. The most notable difference is that a hybrid designed as serial will generally be a "plug-in" hybrid with much greater electric-only range, whereas a parallel will generally have no electric-only range, or very limited electric-only range.

As for "plug-in", that simply means you can recharge the batteries by plugging the car into an electrical outlet. If you can't plug it in, regardless of how efficient it is, all of it's energy still originates from gasoline.


Last Updated 3/26/2012 by Scott Arnold Valid HTML 4.0 Transitional