41 C.F.R. § 301-10.400

The agency may authorize or approve use of:

(a) Taxis, TNCs, or innovative mobility technology companies as specified in § 301-10.420;

(b) Commercial rental automobiles as specified in §§ 301-10.450 through 301-10.452; or

(c) Any other special conveyance when determined to be advantageous to the Government.