From what I understand, it's sort of an extended tutorial set over the course of three in-game days, with each session introducing more and more sophisticated gameplay elements. So the first day is the basics of driving the car, the second introduces KERS and DRS and so on and so forth. There is no word on whether or not the tests can be skipped so that experienced players can just jump straight in, but it may be possible that by completing the tests and meeting certain objectives, experienced players will get offered drives with midfield teams.
When they showed off the game at E3, Codemasters said that the focus for F1 2012 is to give the sport more of a global appeal. They think they've got the gameplay mechanics and graphics right, so now they really want to cater to the wider gaming community, and get interest going among people who might not have much knowledge of what Formula 1 actually is - when it was announced that Formula 1 would go to New Jersey, I noticed a lot of comments from residents who said they weren't familiar with the sport, but they wanted to know more about it, because the idea of the sport held their attention. One that stood out in my mind was a guy who said he couldn't imagine driving down those streets at fifty miles an hour, so the idea of people driving at two hundred miles an hour had him in awe. He then got online, started finding out more about the sport, and is now a dedicated fan. That's the kind of people Codemasters want to reach with this game. They get that Formula 1 has a global appeal, but they don't want to limit the game to people who are already fans of the sport. But in order to do that, they need to ease new players in gently, which is why they introduced the Young Driver Test mode. This should address one of the biggest issues with F1 2010 and F1 2011 - the phenomenally-steep learning curve. When I started playing F1 2011, I jumped into the Virgin and started doing laps of Melbourne, and I was struggling to complete a lap without spinning, much less set a time that was anywhere near anyone else. And when it came time to actually race, I struggled to lap consistently and stay in touch with the guy in twenty-third position. I've never seen a game with a learning curve like that; not even FINAL FANTASY VIII, which has a very complex gameplay mechanic that allows you total freedom in what you do, but the tutorials only give you the very basics.