Bob,
I think the bigger change over the years, at least among the US-spec vehicles, is how the cars were delivered to the dealer. Michael Egan makes an important distinction in his article about US vs. Euro buyers -- the Euro buyer tended to purchase a "bespoke" vehicle with specific options, whereas the US buyer tended to purchase what was on the dealer's lot.
For whatever reason, it appears that, over time, the US market received cars that were increasingly "loaded" with air, auto trans, etc. Technically, these were all still optional, but Pagodas were increasingly fitted with these features towards the end of production.
I've got to think this was based on a combo of profit motive, assumptions about what their particular consumer wanted (i.e., what would sell), and an increasingly affluent market, but I'd love to hear Klaus' insight on this since he's a former D-B employee.
Douglas Kim
New York
USA