Urban traffic congestion representing smog-forming vehicle emissions and the EPA label smog rating

Smog Rating on the Fuel Economy Label: What It Measures

February 23, 2026 8 min read

Quick Summary The EPA fuel economy label includes a Smog rating on a 1–10 scale. It summarizes tailpipe pollutants that contribute to local air pollution (often called “smog-forming emissions”). The Smog rating is separate from the Greenhouse Gas (GHG) rating, which focuses on tailpipe CO₂. A higher score means cleaner tailpipe performance under EPA’s rating system.

Smog rating = local air pollutants (1–10 scale).
GHG rating = tailpipe CO₂ / greenhouse gases (1–10 scale).
Use the Smog rating as a comparison tool—not a prediction of air quality where you live.

Most people focus on MPG, but EPA’s fuel economy label includes emissions ratings too. One of those is the Smog rating, which summarizes how a vehicle performs on certain tailpipe pollutants that contribute to local air pollution.

If you want the full label breakdown (City/Highway/Combined MPG, gallons per 100 miles, cost estimates, and emissions ratings), see: Understanding the EPA fuel economy label.

Where You See the Smog Rating

EPA describes the layout of the fuel economy label in its text version of the gasoline label and in the interactive label. The Smog rating is shown as a 1–10 scale on the label.

What the Smog Rating Measures (EPA)

EPA’s Smog Vehicle Emissions page explains the concept of smog-forming vehicle emissions and why certain tailpipe pollutants matter for local air quality.

The key point for shoppers: the Smog rating is designed to help compare vehicles’ tailpipe performance for smog-forming pollutants under EPA’s rating system.

Interpretation tip: Use the Smog rating to compare two vehicles in the same category (similar size and use case). Like MPG, it is a standardized comparison—not a guarantee of outcomes in your exact driving conditions.

Smog Rating vs Greenhouse Gas Rating

It’s easy to mix these up:

Smog rating relates to local air pollutants.
Greenhouse Gas rating relates to tailpipe CO₂ emissions (and is closely linked to fuel consumed for gasoline vehicles).

If you want the CO₂/fuel relationship explained, see: Fuel economy vs GHG rating.

How to Use the Smog Rating When Shopping

A simple approach:

Pick the vehicle size/class you need first.
Compare MPG and fuel cost to estimate budget impact (try our Cost Per Mile Calculator).
Use the Smog rating as an additional comparison signal if you care about tailpipe pollutant performance.

For a deeper read on how the label is structured, see EPA’s Learn about the Fuel Economy Label page.

Estimate Your Fuel Cost

Use MPG and gas price to estimate fuel cost per mile and annual spending for your driving.

Use the Cost Per Mile Calculator

Frequently Asked Questions

Is a higher Smog rating better?

Yes. On the EPA label, a higher rating indicates cleaner tailpipe performance under the rating system described in EPA’s label documentation.

Does the Smog rating tell me the air quality in my city?

No. It’s a vehicle comparison metric. Local air quality depends on many factors beyond one vehicle’s tailpipe performance, including traffic patterns and regional emissions sources.

Is Smog rating the same as greenhouse gas rating?

No. The GHG rating focuses on tailpipe greenhouse gases (primarily CO₂ for gasoline vehicles). The Smog rating focuses on other tailpipe pollutants that contribute to local air pollution.

Where can I learn more about the label?

Start with EPA’s label resources: Learn about the Fuel Economy Label and the interactive gasoline label.