49 C.F.R. § 663.9 – Audit limitations.

(a) An audit under this part is limited to verifying compliance with
1. (1) Applicable Buy America requirements [section 165 of the Surface Transportation Assistance Act of 1982, as amended,]; and
2. (2) Solicitation specification requirements of the recipient.
(b) An audit under this part includes, where appropriate, a copy of a manufacturer's self certification information that the vehicle complies with Federal Motor Vehicle Safety Standards or a certification that such standards are inapplicable.
(c) An audit conducted under this part is separate from the single annual audit requirement established by Office of Management and Budget Circular A-128, “Audits of State and Local Governments,” dated May 16, 1985.