Illinois Statutes Chapter 30. Finance § 500/45-40. Gas mileage

(a) Specification. Contracts for the purchase or lease of new passenger automobiles, other than station wagons, vans, four-wheel drive vehicles, emergency vehicles, and police and fire vehicles, shall specify the procurement of a model that, according to the most current mileage study published by the U.S. Environmental Protection Agency, can achieve at least the minimum average fuel economy in miles per gallon imposed upon manufacturers of vehicles under Title V of The Motor Vehicle Information and Cost Savings Act.  1

(b) Exemptions. The State purchasing officer may exempt procurements from the requirement of subsection (a) when there is a demonstrated need, submitted in writing, for an automobile that does not meet the minimum average fuel economy standards. The chief procurement officer shall promulgate rules for determining need consistent with the intent of this Section.