Treasury Regulations (26 C.F.R.)
26 CFR § 41.4483-1 — State exemption.
Use of a highway motor vehicle by a State is exempt from the tax imposed by section 4481. For this purpose, the term use by a State means the operation by a State on the public highways in the United States of any highway motor vehicle, whether or not such highway motor vehicle is owned by the State.
Source: official text