Zero Emission Vehicle

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Zero Emission Vehicle ( ZEV ) is the name of an emission-free vehicle in the strongest form of the emissions standards of the CARB legislation of the US state of California . It literally means: "Zero-emission vehicle" and indicates the absence of harmful emissions from combustion gases during operation ( tank-to-wheel ) of the vehicles; However, emissions from brake and tire wear ( fine dust ) and noise are not recorded . The term was coined by the Californian "Low Emission Program" and considers various defined pollutant emissions.

There is no such thing as a ZEV in the literal sense of the word, as emissions occur when every vehicle is operated, for example noise from the drive units such as the engine , transmission and tires or the airstream .

Vehicle structure

The breakdown takes place in various ways according to the type of drive system , the energy used , the type of storage or the substances emitted.

ZEV with electric drive system

ZEV with mechanical drive system


  1. Water is not considered to be harmful exhaust gas if it is emitted close to the ground.
  2. a b Since these drives are based on air breathing, nitrogen oxides are emitted , among other things . The vehicles are therefore not emission-free in the narrower sense, but are classified as ZEV according to Californian legislation.
  3. This emits carbon dioxide, which is not taken into account according to the ZEV guidelines. These vehicles are also not motor vehicles because they do not have a technical drive machine.

Low Emission Program

Advertisements ZERO EMISSION VEHICLE on a trolley bus in San Francisco

The California Air Resources Board (CARB) introduced the Zero Emission Program in 1990 on the basis of the Clean Air Act of the State of California, enacted in 1987. It is part of the Low-Emission-Program, which is designated by the abbreviation LEV (for English Low-Emission-Vehicle or German Low-Emission-Vehicle ) and the respective single-digit version number as an index. This now exists in its 3rd version as LEV 3 and is valid. In this framework program it is already stipulated that by 2018 the proportion of newly registered vehicles that meet the ZEV provisions must be 18% of the total number of newly registered vehicles. In 1997, the Big Seven - the seven automobile manufacturers that sell the largest number of vehicles in California - gave their first consent to develop and produce zero-emission vehicles. However, the originally strict regulation has been revised significantly in favor of the automobile manufacturer. In the meantime, these provisions are no longer only valid in California, but have been adopted over time by a number of US states and are applied there.

The entire body of legislation relates exclusively to certain pollutant emissions from vehicles that are released into the environment during operation ( tank-to-wheel ): carbon monoxide , unburned hydrocarbons NMOG and nitrogen oxides NO x . The CO 2 emissions, which have acquired a new value in the course of the climate discussion, as well as a consideration of the well-to-tank energy supply or the entire energy chain from energy generation to conversion into kinetic energy ( well-to-wheel ) are not taken into account. . A holistic pollutant balance or ecological balance is also not taken into account .

For the environmental balance of a vehicle, however, not only the vehicle-related emissions during operation are relevant, but also the pollution caused by

In contrast to what is known from the European emission standards , in which a stricter limit value must be verifiably complied with on a certain date by all automobile manufacturers for all new models, in the USA and California new standards with stricter limit values ​​are being introduced through so-called phase-in and phase-out introduced the old norm. This is an introduction that is extended over several years, in which the new standard must be complied with by a percentage of all new models that increases each year, while the old standard can be complied with by a percentage of all new models that decreases each year. This applies individually to each manufacturer; the basis for the stated percentage is the entire newly launched vehicle fleet of the manufacturer.

This was also the procedure for the transition from LEV 1 to LEV 2 . LEV 1 has been in existence since the model year (a new model will be launched on the market between August and October of the previous year) 1994 with a corresponding phase-in validity. In the period 2004–2007 it was replaced with a corresponding phase-in or phase-out by LEV 2 in 25% steps.

The transition from LEV 2 to the new LEV 3 control takes place again as phase-in or phase-out, but this time in 20% steps. It started in 2016 and will end in 2020. At the same time, however, there is also a continuous reduction in the mean fleet value for the sum of NMOG and NO x in the extended period from 2015 to 2025, for which the final value of 30 mg per mile is ultimately specified.

Both transitions are shown in the following tables, broken down by year.

Phase-In / Phase-Out LEV 1 / LEV 2
Model year 2004 2005 2006 2007
LEV 1 75% 50% 25% 0%
LEV 2 25% 50% 75% 100%
Phase-In / Phase-Out LEV 2 / LEV 3
Model year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
LEV 2 100% 80% 60% 40% 20% 0% - remains 0% -
LEV 3 0% 20% 40% 60% 80% 100% - remains 100% -
- linear reduction of the mean fleet value for total NMOG + NO x  -

Limit values

The limit values ​​listed in the following two tables are based on a mileage of 50,000 miles. For the mileage of 100,000 miles, which is commonly referred to as "useful life", the limit values ​​to be verified are set slightly higher.

Limits of the California Low Emission Program (LEV 1 )
Emission class CO g / mile NMOG g / mile NO x g / mile
TLEV - Transient Low Emission Vehicle 3.4 0.125 0.4
LEV - Low Emission Vehicle 3.4 0.075 0.2
ULEV - Ultra Low Emissions Vehicle 1.7 0.04 0.2
ZEV - Zero Emission Vehicle 0 0 0
Limits of the California Low Emission Program (LEV 2 )
Emission class CO g / mile NMOG g / mile NO x g / mile
LEV - Low Emission Vehicle 3.4 0.075 0.05
ULEV - Ultra Low Emissions Vehicle 1.7 0.04 0.05
SULEV - Super Ultra Low Emissions Vehicle 1 0.01 0.02
ZEV - Zero Emission Vehicle 0 0 0

CO = carbon monoxide - NMOG = non methane organic gas ( hydrocarbons except methane) - NO x = nitrogen oxide


The following US states have adopted the Californian LEV regulations so far:

  • Arizona, MY 2011
  • Connecticut, MY 2008
  • Maine, MY 2009
  • Maryland, MY 2011
  • Massachusetts, MY 2004
  • New Jersey, MY 2008
  • New Mexico, MY 2011
  • New York, MY 2004
  • Oregon, MY 2009
  • Pennsylvania, MY 2008
  • Rhode Island, MY 2008
  • Vermont, MY 2004
  • Washington, MY 2009

The following US states are still debating whether to adopt the provisions:

  • Colorado
  • Florida
  • Montana
  • North Carolina
  • Utah
  • Wisconsin

Further development of the ZEV requirements since its introduction

After the announcement of the introduction of the ZEV mandate, after lengthy discussions with representatives of the automotive industry, a percentage of 10% of all newly registered vehicles that met the ZEV requirements was determined for the first time for the 2003 model year. The original plan to only recognize vehicles as zero-emission vehicles that actually did not emit anything, however, was dropped after the most violent interventions by the automotive industry. According to the original version, such vehicle drives could only be fuel cell vehicles and battery-powered electric vehicles . While hydrogen-powered vehicles were still under development in 2003, battery-electric vehicles were developed early on by all major manufacturers. However, their production was not economical, which is why the manufacturers pushed for a relaxation of the CARB laws and after their implementation almost completely abandoned the development of the ZEV and in some cases even scrapped the existing, functional ZEV vehicles. The documentary Who killed the electric car? from 2003.

Examples of ZEV vehicle developments from this phase:

For this reason, from 2003 (the start of ZEV vehicles), vehicles were also partially recognized that had small or very clean drives or - like the recently introduced hybrid vehicles - could cover a short distance purely electrically. This resulted in a “dilution” of the original share of 10% ZEV vehicles, which is why the name LEV (literally: “low-emission vehicle”) was established by the manufacturers. A gradual increase in the ZEV share from 4.5% in 2018 to 22% from 2025 is currently planned.

Which automobile manufacturers are affected

The development of battery-powered electric drives, or those that get the energy they need from a fuel cell and have a hydrogen tank, is not economically viable at all by all automobile manufacturers who sell automobiles in California. The Air Resources Board, as the responsible authority, was always aware of this. A staggered solution has therefore been created for such smaller companies, which looks like this:

Affected by automobile manufacturers
Company independence Sold per year in California Affected by the ZEV mandate comment
Not independent up to 4,500 not affected
independently up to 10,000 not affected
4,501 to 60,000 affected but the ZEV requirements can only be met with PZEV vehicles (bronze status)
more than 60,000 fully affected the manufacturers affected by this are: Daimler, VW, General Motors, Ford, Toyota, Honda, Hyundai (the "big seven")

An example calculation for these manufacturers could look like this:

Sample calculation
Sold vehicles from one manufacturer 100,000
As a result, the manufacturer is obliged to offer 10% vehicles that meet ZEV criteria: 10,000
The number could then be composed like this:
Credits from ZEV vehicles 2000
Credits from AT-PZEV vehicles 2000
Credits from PZEV vehicles 6000

Individual evidence

  1. 2003 Zero Emission Vehicle Program Changes. (PDF; 127 kB) CARB (Fact Sheet), accessed on July 28, 2017 (English).
  2. a b c d 2011/2012 | Worldwide Emissions Standards | Passenger Cars and Light Duty Vehicles. (PDF; 2.1 MB) Delphi , archived from the original on November 19, 2012 ; accessed on July 28, 2017 (English).
  3. a b 2017/2018 | Worldwide Emissions Standards | Passenger Cars and Light Duty Vehicles. (PDF; 7.5 MB) Delphi , archived from the original on July 28, 2017 ; accessed on July 28, 2017 (English).
  4. ^ General Motors EV1 . Data sheet ElWeb; Retrieved January 29, 2012
  5. ^ The A-Class Electric Vehicle, Powered by the ZEBRA Battery System . (PDF) Prospectus of Daimler-Benz AG, 12/1997; Retrieved January 18, 2012
  6. Zero-Emission Vehicle Standards for 2018 . (PDF) ARB California; accessed September 26, 2014