49 CFR §663.9

1. (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.
2. (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.
3. (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.