With an increased focus on air quality in this country, there are more and more incentive programs available to diesel equipment and vehicle owners to encourage them to replace older equipment with newer, cleaner ones, to rebuild old engines, or to retrofit current engines with new technologies that help lower emissions. However, in order to apply for funding from many of these programs, you must collect detailed information on your current equipment and/or vehicle(s). Gathering all of the necessary information for program application can prove daunting, as the information requested is not always readily available. Information of interest may include, among others: Equipment or Vehicle Type, Engine Make, Engine Model, Engine Model Year, Engine Displacement, Engine Horsepower, Engine Tier Level, and Annual Activity. The purpose of this guide is to aid in collecting the information needed to create an accurate inventory for construction fleet. The information collected from vehicles/equipment, with the aid of this guide, will assist in assessing fleet for its ability to qualify for various clean diesel incentive programs. This guide also outlines best practices for collecting the required information and removing some of the barriers to finding and identifying the required information about fleet. Using this guide to collect vital information about fleet will aid in identifying ways to make fleet "cleaner" through volunteer measures, or to meet state and federal mandates.