Every vehicle is required to have a permanent underhood emission label (known as the Vehicle Emission Control Information label) that can usually be found under the hood near the engine.

You will find the engine size (displacement) and the Underhood Label Identification Number (engine family) and other emission information on the underhood label.

The engine size will normally be shown in units of liters (3.2 L = 3.2 liters).

The Underhood Label Identification Number is 12 characters long (including the decimal point).

Make sure that the engine size and Underhood Label Identification Number on the label of the vehicle you are going to purchase (or on your current vehicle) matches those in this guide. This is the only way to verify that you are purchasing the vehicle with the EPA ranking you desire.

EPA's Green Vehicle Guide also provides information on clean vehicles and how you can purchase one.