The Engine Manufacturers Association (EMA) retained MathPro Inc. to estimate the per-gallon costs, investment requirements, and technology performance requirements for reducing the average sulfur content of on-road and off-road diesel fuel to specified average levels, ranging from 150 ppm to 2 ppm. The study applied to refining capacity in PADDs 1, 2, and 3. The study delineated the economics of diesel fuel sulfur control using advanced, but commercially established, desulfurization technology. The representation of this technology in ARMS is based on proprietary data obtained from the technology developers, as the result of a data collection initiative jointly sponsored by EMA and the American Petroleum Institute (API).

The study employed formal refinery LP modeling using the ARMS refinery modeling system. Results of the analysis were reviewed by API and then made available to EPA and other interested parties in conjunction with EPA's consideration of national ultra-low-sulfur standards for diesel fuel in connection with Tier 2 diesel engine emission standards promulgated by EPA.