Copyright has zero application here unless you redistribute Tesla's code or binaries. Reverse-engineering is a legal practice (in US law, at least).

Reverse engineering to utilize software you didn't pay for and don't have a license or some other legal authority to use is unlikely to pass muster legally, versus for interoperability purposes.

https://www.eff.org/issues/coders/reverse-engineering-faq (Control-F "What Exceptions Does DMCA Section 1201 Have To Allow Reverse Engineering?")

https://www.theverge.com/2022/7/12/23204950/bmw-subscription...

Only for the kinds of “use” that involve the exclusive rights of the copyright owner (“use” generally does not), and even then not always, because there are exceptions to copyright.

If you sell me a book, I'm not allowed to copy that book and sell those copies. I am allowed to chop it up and and repaste my own copy however I see fit.

If I'm wrong and current copyright law does not permit this kind of thing, then current copyright law is bad and should be changed.

[1] https://www.law.cornell.edu/uscode/text/17/1201 (17 U.S. Code § 1201 - Circumvention of copyright protection systems)

[2] https://www.law.cornell.edu/definitions/uscode.php?width=840... (circumvent a technological measure (3) As used in this subsection— (A) to “circumvent a technological measure” means to descramble a scrambled work, to decrypt an encrypted work, or otherwise to avoid, bypass, remove, deactivate, or impair a technological measure, without the authority of the copyright owner; and (B) a technological measure “effectively controls access to a work” if the measure, in the ordinary course of its operation, requires the application of information, or a process or a treatment, with the authority of the copyright owner, to gain access to the work.)