Misleading “zero emission vehicle” label is here to stay

Zero emission vehicles (ZEVs) are commonly understood to be modern vehicles that do not produce tailpipe emissions. The phrase “ZEV mandate” is now used to identify California’s effort to phase out the sale of internal combustion vehicles by 2035, and most people naturally assume that the ambitious new regulations will prohibit the sale of all vehicles powered by gasoline. But California’s use of the ZEV designation is actually quite misleading, as it includes plug-in hybrid electric vehicles (PHEVs) that, like all hybrids, have tailpipes and burn petrol. PHEVs are capable of travelling moderate distances on imported electric fuel, but it is entirely disingenuous to categorize them as ZEVs. While some PHEVs do deliver significant emission reductions, many do not, and their inappropriate categorization distorts public perceptions about the relative merits of the major green powertrains. California’s parlance excludes non-plug-in hybrid electric vehicles (HEVs) from the ZEV category, and the inequitable use of language mirrors an arbitrary bias against HEVs that permeates electric vehicle advocacy groups.

The California Energy Commission provides authoritative data on statewide ZEV sales, and their online graphics illustrate the accepted meaning of the ZEV misnomer in governmental nomenclature. One graphic describing California’s light duty vehicle population compares the total quantity of registered “ZEVs” and “non-ZEVs” that were on the road at the end of 2022. The 1,111,028 recognized ZEVs include 763,557 battery electric vehicles (BEVs), 335,574 PHEVs, and 11,897 fuel cell electric vehicles (FCEVs). The 28,189,748 non-ZEVs include 26,188,730 conventional gasoline vehicles, 1,394,237 HEVs, 598,147 diesel vehicles, and 8,634 vehicles labeled as “other”. The descriptors used in the graphic highlight the emissions from HEVs while downplaying the emissions from PHEVs. HEVs are referred to as “gasoline hybrids”, but PHEVs are identified without mentioning their fuel. The three favored powertrains classified as ZEVs are presented alongside their standard abbreviations, BEV, PHEV, and FCEV, but the conventional hybrid powertrain is not paired with its standard abbreviation, HEV. Ardent BEV advocates object to classifying hybrids as EVs and vehemently reject the HEV abbreviation. They tend to look the other way if a hybrid has plug-in capability, and the commission’s graphic is consistent with this arbitrary prejudice.

A similar graphic posted by the commission shows ZEVs making up 25% of California’s light duty car sales in 2023. Sales figures from the last three weeks of December are yet to be tallied, but the encouraging year-to-date ZEV totals include 379,727 BEVs, 64,091 PHEVs, and 3,143 FCEVs. California’s cumulative ZEV sales were approaching 2 million as 2023 was coming to an end, with 493,964 gas-burning PHEVs contributing to the impressive total.

It may seem useful to distinguish BEVs, PHEVs, and FCEVs from other vehicles powered exclusively by gasoline or diesel, but the ZEV misnomer has now become the basis for dubious public policies favoring PHEVs over HEVs. Pervasive bias against HEVs is unfortunate, as efficient HEVs are environmentally superior to inefficient PHEVs and are making an important contribution to the mitigation of climate change. It would be more forthright to confine the ZEV appellation to fully electric BEVs and hydrogen powered FCEVs, but such a change seems highly unlikely.