I think the most exciting thing (and we're way behind schedule on this, a lot of this could have easily been done literally 30 years ago, no problem at all), is caravan functionality, where a group of cars moves together. If you imagine 20 cars at a standstill for some reason, if they begin to move forward slowly but at the same time (less than 50 millisecond apart) because they're coordinated then they can get up to speed almost as fast as if it were only just one car (let's say they have to speed up a bit more slowly for a safety allowance). But if you factor in human response time, it can be a phantom traffic jam. There is no reason for a traffic jam because there is clear road all the way ahead of the group - yet a traffic jam slowly makes its way back anyway. Like this:
https://www.youtube.com/watch?v=goVjVVaLe10&t=1m55scoordinating this stuff doesn't require computer vision or truly self-driving cars or anything like it and could have been done 30 years ago (1986) over an AM radio standard and some kind of coordination between cars - just nobody sat down and designed that standard.
today wireless coordination technology offers dozens of choices (in the gigahertz domain) and caravans could be assembled all but "trivially", cars can know where they are via gps with no problems at all. That would be an exciting move forward. Of course, it only works when everyone is doing it, but if just a few traffic jams instantly disappear (the ones where are the cars happen to have caravan functionality and coordinate) it would improve things for everyone: the traffic jam will disappear whenever it bunches up in a way that happens to consist of coordinated cars. (e.g. a 3-car phantom jam slowly moving backward will disappear whenever it crosses 3 caravan-enabled cars - not every car has to have this functionality). But I haven't read anything about Tesla coordinating even with other Teslas, let alone some standard of intercar coordination. A shame - this stuff is way easier than the self-driving stuff Tesla and others are doing. It's very low-hanging fruit.