Smog Rating
- This rating reflects vehicle tailpipe emissions that contribute to local and regional air pollution, creating problems such as smog, haze, and health issues.
- Vehicles that score a 10 are the cleanest.
- Light duty cars and trucks must meet either federal [EPA] or California [CARB] emission requirements. Individual states choose whether vehicles sold there meet either the federal or California emission requirement. Within both the federal and California system, automakers may choose from a range of eligible emission standards for each vehicle.
- Model year 2018 and later: The smog rating chart has been recalibrated to reflect new, more stringent Tier 3 emission standards. This is good news, as Tier 3 cars and trucks are much cleaner. This recalibration makes better use of the entire smog rating scale and allows for more useful comparisons between vehicles. Please note: Even though ratings appear to be going down, vehicles are not getting dirtier. A MY 2018 and later smog rating of 3 is about the same as a MY 2017 smog rating of 6.
- Before a new vehicle model can be sold, sample vehicles are tested under tightly controlled conditions. Their tailpipe emissions are captured and measured using sophisticated monitoring techniques. The results determine the emission standard that the vehicle meets.
- Emission standards are for the major pollutants in vehicle exhaust:
- NMOG, NMHC, or THC—types of carbon-containing compounds, including hydrocarbons
- NOx—Oxides of Nitrogen, which combine with hydrocarbons to create smog
- PM—Particulate Matter, tiny particles of solid matter that lodge in the lungs and deposit on buildings
- CO—Carbon Monoxide, a colorless, odorless, poisonous gas
- HCHO—Formaldehyde, a lung irritant and carcinogen
Rating Scales by Model Year (MY)
| Rating | EPA Tier 3 | CARB LEV III |
|---|---|---|
| 10 | Bin 0 | ZEV |
| 9 | -- | -- |
| 8 | -- | -- |
| 7 | Bin 20 | SULEV20 |
| 6 | Bin 30 | SULEV30 |
| 5 | Bin 50 | ULEV50 |
| 4 | Bin 70 | ULEV70 |
| 3 | -- | -- |
| 2 | Bin 125 | ULEV125 |
| 1 | Bin 160 | LEV160 |
*Given full implementation of federal (EPA Tier 3) and California (CARB LEVIII) emission standards, older (Tier 2 and LEVII) emission standards no longer appear on the smog rating chart.
| Rating | EPA Tier 2 | EPA Tier 3 | CARB LEV III |
|---|---|---|---|
| 10 | Bin 1 | Bin 0 | ZEV |
| 9 | -- | -- | -- |
| 8 | -- | Bin 20 | SULEV20 |
| 7 | Bin 2 | Bin 30 | SULEV30 |
| 6 | -- | Bin 50 | SULEV50 |
| 5 | Bin 3 | Bin 70 | SULEV70 |
| 4 | -- | -- | -- |
| 3 | Bin 4 | Bin 125 | SULEV125 |
| 2 | -- | -- | -- |
| 1 | Bin 5-8 | Bin 160 | SULEV160 |
| Rating | EPA Tier 2 | EPA Tier 3 | CARB LEV II | CARB LEV III |
|---|---|---|---|---|
| 10 | Bin 1 | Bin 0 | ZEV | ZEV |
| 9 | Bin 2* | Bin 20 | PZEV | SULEV20/PZEV |
| 8 | Bin 2 | Bin 30 | SULEV II | SULEV30 |
| 7 | Bin 3 | Bin 85/Bin 70/Bin 50 | ULEV70/ULEV50 | |
| 6 | Bin 4 | Bin 125/Bin 110 | ULEV II | ULEV125 |
| 5 | Bin 5 | Bin 160 | LEV II | LEV160 |
| 4 | Bin 6 | LEV II option 1 | ||
| 3 | Bin 7 | |||
| 2 | Bin 8 | SULEV II lg trucks | ||
| 1 | ULEV & LEV II lg trucks |
*Vehicle must also be certified to CA PZEV.
| Rating | EPA Tier 2 | CARB LEV II | CARB LEV III |
|---|---|---|---|
| 10 | Bin 1 | ZEV | ZEV |
| 9 | Bin 2* | PZEV | SULEV20/PZEV |
| 8 | Bin 2 | SULEV II | SULEV30 |
| 7 | Bin 3 | ULEV70/ULEV50 | |
| 6 | Bin 4 | ULEV II | ULEV125 |
| 5 | Bin 5 | LEV II | LEV160 |
| 4 | Bin 6 | LEV II option 1 | |
| 3 | Bin 7 | ||
| 2 | Bin 8 | SULEV II lg trucks | |
| 1 | ULEV & LEV II lg trucks |
*Vehicle must also be certified to CA PZEV.
| Rating | EPA Tier 2 | CARB LEV II |
|---|---|---|
| 10 | Bin 1 | ZEV |
| 9 | PZEV | |
| 8 | Bin 2 | SULEV II |
| 7 | Bin 3 | |
| 6 | Bin 4 | ULEV II |
| 5 | Bin 5 | LEV II |
| 4 | Bin 6 | LEV II option 1 |
| 3 | Bin 7 | |
| 2 | Bin 8 | SULEV II lg trucks |
| 1 | ULEV & LEV II lg trucks |
| Rating | EPA Tier 2 | CARB LEV II |
|---|---|---|
| 10 | Bin 1 | ZEV |
| 9 | Bin 2 | SULEV II |
| 8 | Bin 3 | |
| 7 | Bin 4 | ULEV II |
| 6 | Bin 5 | LEV II |
| 5 | Bin 6 | LEV II option 1 |
| 4 | Bin 7 | |
| 3 | Bin 8 | SULEV II lg trucks |
| 2 | ULEV ll lg trucks | |
| 1 | LEV ll lg trucks | |
| 0 |
| Rating | EPA Tier 2 | CARB LEV II |
|---|---|---|
| 10 | Bin 1 | ZEV |
| 9 | Bin 2 | SULEV II |
| 8 | Bin 3 | |
| 7 | Bin 4 | ULEV II |
| 6 | Bin 5 | LEV II |
| 5 | Bin 6 | LEV II option 1 |
| 4 | Bin 7 | |
| 3 | Bin 8 | SULEV II lg trucks |
| 2 | Bin 9 | ULEV ll lg trucks |
| 1 | Bin 10 | LEV ll lg trucks |
| 0 | Bin 11 |
Frequent Questions on the Smog Rating
Pollutant Emission Levels for Each Standard
-
Federal and California Light-Duty Vehicle Emission Standards for Air Pollutants (PDF) (4 pp, 244 K, September 2019, EPA-420-B-19-043, About PDF)
- California Low Emission Vehicle (LEV III) Exhaust Emission Standards