The report includes state- and county-level results based on a review of over 150,000 unique invoices containing delete tuning or hardware. These invoices cover sales of delete parts in all 50 states and approximately 83% of counties in the United States. The collected evidence also shows that approximately 50% of tampering occurs when vehicles are three years of age or less, and over 85% of tampering occurs by the time vehicles are eight years old.

The report focuses on delete tuners installed in Class 2b and 3 heavy pickup trucks, such as the Chevrolet Silverado and Dodge Ram 2500. However, such devices have been also installed in other types of vehicles. The EPA believes that this conduct occurs within most or all categories of vehicles and engines, including commercial trucks, passenger vehicles, pickup trucks, motorcycles, forestry equipment and agricultural equipment.

People tamper vehicles and engines for a variety of reasons. Some remove emissions controls to avoid the cost and time required to maintain emissions controls, while others tamper to increase fuel economy or power, or to customize their vehicle. Emission tampering devices are commonly available from many, usually smaller size, suppliers.