US: Vehicle Definitions

Overview
The United States Environmental Protection Agency (EPA) defines vehicle and engine types for the purposes of federal emissions regulations.

California, which sets its own emissions standards for some categories of vehicles, uses similar vehicle definition as the federal EPA, but with some minor differences.

Technical Standards
The following table summarizes vehicle classifications as defined by the EPA:

Diesel engines used in heavy-duty vehicles are further divided into service classes by GVWR:
 * Light heavy-duty diesel engines (LHDDE): 8,501 - 19,500, e.g for use in HDV classes 2b - 5
 * Medium heavy-duty diesel engines (MHDDE): 19,501 - 33,000, e.g. for use in HDV classes 6-7
 * Heavy heavy-duty diesel engines (including urban bus) (HHDDE): > 33,000, e.g. for use in HDV class 8

Links
EPA Vehicle Weight Classification page