I get it, the alternative is something akin to a pyramid scheme - updates have to be funded by future sales.
That works for me if I’m already a customer - but the company has to keep selling to keep funding their services.
However taken to the extreme it risks the company implementing some kind of planned obsolescence to provide that funding. And it doesn’t incentivize efficiency (making the service simply cost less to provide over time) any better than a subscription model. Not sure which is less evil in the long term.
Maybe by wanting no subscription I’m just being selfish.
If the feature is 100% local to the car I’d like a one time purchase.
If the feature relies on other services, such as manufacturers mapping roads, then I can support some subscription for ongoing maintenance.