* No comprehensive vehicle registry: The US doesn't maintain a continuously updated registry of every vehicle ever sold. Registrations are handled at the state level, and data isn't consistently collected and aggregated nationally for this level of detail (engine, transmission, etc.).
* Scrapping and parts cars: Many cars are scrapped or disassembled over time, meaning they are no longer whole vehicles.
* Exports: Some cars may have been exported outside the US.
* Data inconsistencies: Even if records *were* kept, there would likely be inaccuracies due to errors in initial sales figures, registration changes, and record-keeping inconsistencies over the decades.
While you might be able to find estimates based on production numbers and estimated survival rates, these are just that—*estimates*. They could be significantly off the mark.
