"solving Europe's road congestion"
Alternatively, instead of trying to "solve" the problem by creating a new one (how to control these mini-copters), how about making it easier for people to get from A to B without the massive waste of space that involves putting *one* person in a vehicle designed to carry four (or five, or seven)?
It's all very well to whinge about "independence" etc, but when you're doing the same journey, day in, day out, how many times will you actually *need* that independence? On that day, fine, use your own car, but don't be selfish and think "well, I *might* need it so I'll take it today, and tomorrow, and the next few days too..."
Make it easier for people to ride bicycles or motorbikes. Put more money into mass transit systems. For example down here in Portsmouth there was a plan for a light transit system to take the load off the M275, London Road and Eastern Road which are the only three ways off Portsea Island (and if one gets blocked, it can gridlock the whole city!) but that was cancelled when the DfT refused it funding back in 2005, so we're stuck with lots of people driving out of the city in the morning, then back in in the evening which is ludicrously wasteful.
Such systems are hardly rocket science, we just need the will to make them happen!