Guys, just to be clear. I think a lot of people think I'm saying all under 25s are irresponsible and I'm not saying that at all. I'm saying they lack experience (which of course is also true for older drivers who start driving when they are old too, but is is true of every young driver necessarily).
What I said was that no matter how sensible or not sensible you are when you are 21 you don't have the awareness and the intuition that only experience brings. Its even worse in a powerful car because you also need to know what the bangers on the road can drive like. Yes, your brand new GTI with its disc brakes can bring you to a halt in record time, but what about that busted Citroen with the bald tyres? How will you take into account that cars performance if during your learning period (the 5 years after you pass) you get into a modern powerful car?
Even if as a young driver you never make any mistakes (and everyone makes many mistakes every single journey), thats not the point, other road users will make mistakes, frequently. It takes years of driving to have built up the knowledge of what might happen, what pre-emptive action to take, what to do if it does happen and what limitations you and other drivers have. Its not even just other road users, what about pedestrians? Half a second can mean the difference between hitting that child that ran out in the road and stopping in time. There are different road conditions to take into account, different mechanical faults, road layouts vary across the country, different vehicles behave differently, bikes behave differently, push bikes, pedestrians etc etc etc...
So I'm not saying everyone young is reckless, but no matter how careful you are its going to take years before you are an expert and that applies to every young person. I don't think (personal opinion) non-experts should be driving 200bhp cars. Sorry.