Ill. Admin. Code tit. 35, § 241.141 – Recordkeeping Requirements

a) Owners or operators of covered fleets shall retain a copy of the title or lease for each motor vehicle in the fleet.
b) For each motor vehicle that the owner or operator is claiming is exempt pursuant to Section 241.111(a)(10) of this Part, the owner or operator must retain records showing the roundtrip calculation exempting the motor vehicle under the definition of capable of being centrally fueled, as set forth in Section 241.102 of this Part.
c) For each motor vehicle in a covered fleet located outside of the covered area that the owner or operator is claiming is not primarily operated in the covered area, the owner or operator must retain records demonstrating that the motor vehicle is not primarily operated in the covered area, as set forth in the definition for primarily operated in the covered area in Section 241.102 of this Part.
d) For each converted motor vehicle, the covered fleet owner or operator must retain documentation that the motor vehicle meets the applicable certification requirements for converted motor vehicles in 40 CFR Part 88, Subpart C, incorporated by reference at Section 241.104 of this Part.
e) For fleets that are centrally fueled at a location that is owned, operated or controlled by the covered fleet owner or operator, the owner or operator must retain monthly records of the amount and type of bulk fuel purchased.
f) Fleet owners and operators of non-covered fleets who elect to participate in the credit program, as set forth in Subpart C of this Part, must maintain the following records for each motor vehicle that they are using to generate credits:
1. 1) A copy of the title or lease; and
2. 2) For each converted motor vehicle, documentation that the motor vehicle meets the applicable certification requirements for converted motor vehicles in 40 CFR Part 88, Subpart C, incorporated by reference at Section 241.104 of this Part.
g) The records required in this Section shall be retained by the owner or operator for at least three years and shall be made available immediately to the Agency upon request. Notwithstanding the above requirement, titles or leases to vehicles no longer under the control of the owner or operator need not be retained.