Register MIME type application/car with IANA about specs HOT 1 OPEN

https://datatracker.ietf.org/doc/html/rfc6838#section-3.1

3.1. Standards Tree
The standards tree is intended for types of general interest to the
Internet community. Registrations in the standards tree MUST be
either:

1. in the case of registrations associated with IETF specifications,
   approved directly by the IESG, or

2. registered by a recognized standards-related organization using
   the "Specification Required" IANA registration policy [RFC5226]
   (which implies Expert Review).
   ...
   In the second case, the IESG makes a one-time decision on whether the
   registration submitter represents a recognized standards-related
   organization; after that, a Media Types Reviewer (Designated Expert
   or a group of Designated Experts) performs the Expert Review as
   specified in this document. Subsequent submissions from the same
   source do not involve the IESG. The format MUST be described by a
   formal standards specification produced by the submitting standards-
   related organization.

from specs.