Ideally, I think what you want is an upgradable car, like a jet fighter, that can maintain a single body and have replaceable components.

I don't think we'll ever get that though because consumers are too fickle, and there is no real benefit to the manufacturer.

Yes, even for cars with significant onboard user-oriented software systems (like the Prius) there is no upgrade path. It seems we are currently in the "early cellphone" phase, rather than the "iPhone" era where automotive software is concerned.

What is so upgradeable about the hardware in the iphone ?

Note my use of the word "software".