You can’t make a transceiver and chip for this kind of deployment that can only be used by the right people. Either the secrets will leak or the implementation will have vulns or both.
Oh, I was on cypherpunks in 01992, so I know about the Clipper Chip. But in this case you don't need to keep any secrets from the owner of the vehicle; they're free to attach a debugging connector to their own transceiver and read it at any time. The idea is to make their car anonymous to other people, except for law enforcement, not to themselves.
Maybe you think there's no way that the transceiver can successfully authenticate those law-enforcement requests without containing secrets. It can; it only needs the public key of a root CA.
You can’t make a transceiver and chip for this kind of deployment that can only be used by the right people. Either the secrets will leak or the implementation will have vulns or both.