Your most readily understood answer is going to be simply made obsolete. Here is why looking for something else can lead to problems:
Attempting to capture a precise meaning in a single word without context will often lead to ambiguities. While you provide context in one example, it doesn't necessarily apply in similarly worded examples.
To illustrate this, let's start with your context:
The automobile made the horse and buggy obsolete.
I'll show some counterexamples further on that would make you question the value of these choices. But using some of the most up-voted suggestions, you can ask yourself: are these statements necessarily going to mean the same?
The automobile superseded the horse and buggy.
The automobile supplanted the horse and buggy.
The automobile deprecated the horse and buggy.
The automobile displaced the horse and buggy.
The automobile eclipsed the horse and buggy.
For each of these words, there are multiple definitions. They are not all consistent with "make obsolete":
supersede: to succeed to the position, function, office, etc., of
supplant: to take the place or move into the position of
deprecate: to express disapproval of; deplore.
displace: to move from the usual or correct location
eclipse: to surpass; outshine
In choosing "the best words", you are still left with the job of ensuring that what the listener hears is the same as what you say.
If you changed the context, do these highlighted words mean "made obsolete"?
Here are the counterexamples:
In the national park, federal law supersedes state law.
This year, imported cars are expected to supplant domestically produced vehicles.
The scientists were mocked in a move to deprecate the oil industry.
The war displaced millions of people.
When Ryun eclipsed the four minute mile, it became a realistic goal for many to strive for.
It should be obvious that none of these statements conveys the notion of made obsolete.
Words with multiple meanings have their place, and they only convey their intended meaning with the right context. None of the examples above about the automobile will necessarily be understood to mean "made obsolete" except to the person who already knows that simple fact.