There have been not a few changes.
Tesla has been selling the Model S since 2012. While many automakers would consider making a major refresh to the model after this much time, the California company's CEO, Elon Musk, has said (tweet embedded below) that there is "No such thing as a “full refresh” at Tesla or even a model year." Instead, the company does partial upgrades every month whenever "a new subsystem is ready for production." This video (above) from the Black Tesla YouTube channel is interesting then, as it investigates some of the detectable changes the full-size sedan has seen since 2014.
More on Tesla Model S changes
An owner of a Model S P85 from 2014 recently upgraded to a 2018 P100D version and lays out all the changes he's been able to notice. The footage dwells pretty much on the interior and the driving feel. Obviously, there is a difference in exteriors as the car got a new fascia in early 2016, and there are probably a good many changes to the bones beneath the aluminum skin as well. While some elements of the transformation may be subtle, there is a theme our narrator returns to: increased refinement.
Besides the physical changes, the software systems of Tesla vehicles are constantly improved. In a tweet (embedded below), Musk maintains that this is one of the factors that helps "a Tesla retains so much value over time." Though our host doesn't dive too deeply into the software changes — there have been a lot in the past four years — it is something to keep in mind as well. Enjoy!
No such thing as a “full refresh” at Tesla or even a model year. Our cars are partially upgraded every month as soon as a new subsystem is ready for production. There is no cadence.
— Elon Musk (@elonmusk) October 9, 2018
True, but this will improve dramatically over next several months & all Tesla cars ever produced (except early Roadsters) will get improvements for free. Continuous, free over-the-air software updates is a big part of why a Tesla retains so much value over time.
— Elon Musk (@elonmusk) October 17, 2018
Giving my impressions on going from a 2014 P85 to a 2018 P100D. Highlighting features and updates other owners considering upgrading or those looking CPO might want to know.