49 CFR §512.17

1. (a)When information claimed to be confidential is requested under the Freedom of Information Act, the determination will be made within twenty (20) working days after NHTSA receives such a request or within thirty (30) working days in unusual circumstances as provided under 5 U.S.C. 552(a)(6)(A). However, these time periods may be extended by the Chief Counsel for good cause shown or on request from any person. An extension will be made in accordance with 5 U.S.C. 552(a)(6)(A), and will be accompanied by a written statement setting out the reasons for the extension.
2. (b)When information claimed to be confidential is not requested under the Freedom of Information Act, the determination of confidentiality will be made within a reasonable period of time, at the discretion of the Chief Counsel.