https://peloton-tech.com - I mean, that's just one company, I think there are a handful working on just the problem you're talking about.

If cars could assemble into close convoy trains on multi-lane highways / motorways / autoroutes / whatever, then it would probably also solve electric car range for many people - you only care about range on relatively long distance journeys, and you're likely to be doing those on major multi-lane carriageways. If you could split the air resistance between a bunch of other vehicles then you'd add considerably to the range. I similarly don't understand why we're not trying to solve that instead. As you say, it seems easy compared to full autonomous driving.

This could be solved for cheaper with better public transport.