Indeed, this seems to be exactly the area where the Data Act could be used to regain access. Unfortunately it seems that it's not possible to directly sue (e.g.) Volkswagen to get access, unlike the GDPR where you have direct standing under article 79 [1].

There doesn't seem to be much written about enforcing the Data Act, so I looked at the regulation directly. Article 39 [2] seems to require to first lodge a complaint with the competent authority as designated by the member state of your residence. Then when that authority invariably fails to act – I have no idea which timeframe we're talking about here – you can "in accordance with national law, either have the right to an effective judicial remedy or access to review by an impartial body with the appropriate expertise". But then you are suing that authority, and not the company directly (edit: I was originally unsure about who to sue under article 39, but 39(3) does clarify that it is the authority).

I would very much like to be wrong about this. I can imagine Muñoz vs. Superior Fruiticola applies [3] ("it must be possible to enforce that obligation by means of civil proceedings"), but I'm not at all sure, and it's a much weaker route than the one which the GDPR explicitly describes.

Would anyone know or have better references on how to enforce the Data Act, preferably individually?

[1] https://gdpr-info.eu/art-79-gdpr/

[2] https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=OJ:...

[3] https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELE...