@Rich - The existing term in
@Rich - The existing term in the industry at the time GM designed the Volt is "PHEV". That term has existed for a long time and is a well known acronym/phrase. Additionally, the Chevy Volt is also described as a Series Hybrid, another term with a long history.
EREV is a term invented by GM's marketing department. The company obviously needed a way to claim they'd built an electric car because everybody sees GM as the killer of the electric car thanks to a certain movie. Hence they invented EREV so they could call the Volt an electric car, when the existing terms in the industry are PHEV and Series Hybrid.
As for whether the Government thinks the Volt is a PHEV ... take a look at the EPA sticker. Take a look at fueleconomy.GOV .. both say the Volt is a PHEV.