I have mixed feelings about this. On the one hand, if a warrant is issued based on evidence of a crime (e.g. high speed accident, people killed) and the data is extracted after the fact...what is the big deal? The key would be sufficient evidence of a crime, and a warrant being issued for the search. Vaccuuming electronic data as part of a search is legitimate. So, would you support there being black boxes in people's houses that would record conversations and other sounds, and movements - that would only be searched in the event of probable cause of a criminal act taking place at that house? Don't worry, if you haven't committed a crime, there's nothing to worry about?
No. But the black boxes in the cars are there for reasons other than just recording. They are used for control of the engine and to detect problems. You, on the other hand, are proposing something completely different.
If the data chips in your car concern you, just buy an older model car (there are plenty in good condition down South) and maintain it. No more worries.