Haven't heard about that classification. It looks helpful indeed. As for TrackMania... I also had great times with TrackMania Sunrise. Ah, my mind wandered to the hours spent on nailing the tracks for an Author Medal... And then the next one. I always thought it's such a neat game, because it's stripped of all of those unimportant features you have in other games - like earning some reputation, money, new cars, some poor background stories. In TrackMania all you're left is the challenge (as you mentioned) to do it faster than the previous time. All this talk about TrackMania made me want to play it...
If you download the Trackmania 2 (Stadium / Valley / Canyon), you can play the full game for your first 48 hours unlimited free and after that one hour every day for free. And when you're done, you can head to this other thread from today!
In the end I think I'll give up TrackMania, at least for now. It'll be better, if I spend this time practising on the guitar, reading and looking for a job. Maybe after I'll find a job, I'll give it a try.