I am sorry for the title name, I do not know how I should probably call it..
To start off, I see some suggestions which do not have to do with a race game. They ofcourse do have some ideas of RPG. I am not trying to prove anyone wrong, this is what I thought.
When I think 'quests' and 'racing' I automatically start thinking of the game "road trip".
that is a pretty old game but unfortunately does not have anything to do with RPG. but that is not the point.
the point is that to get better things in the game you had to race,
you could join a race by going to the so called "q factor" (a factory where you could change parts, or just join a race)
ofcourse that's not what I ment of what reminds me to quests.
there were like 8 or 9 towns.
every town in his own style. (represents a part of the word (like the sahara desert which is dry and sandy.)
by going into houses (or sometimes random people who drive outside) could give you a quest.
sometimes you have to find something for them. (common for RPG)
sometimes a random found item could be returned to a close police station.
sometimes a random 'car' get's mad by someone else and asks you if you could beat him for them.
these quests are pretty short though, keep in mind that these were examples out of the game.
(one example of a bigger quest would be to search for more things for someone so he can make that super exclusive part only he can make)
in the game I talk about it would give you a 'stamp', the stamp is so you can see what you allready did.
think of it like achievements. instead of just a stamp you could involve money or even XP maybe even some parts for your car to upgrade and take on better players.
in this way you have the basic trackmania idea, that it has to do with cars, but also RPG.
I could think of tons of things more that could be in such a game.
I want to say: I do not know how you imagined how the game should be. I do not know if it has to be with characters which look like real humans or fantasy alike.. but I thought, this is nadeo, this is based of a racing game, why not combine racing and quests. instead of going to dream making it another fantasy game like WoW or some other online game.
If I gave some ideas, I am happy.
If this is a shot in the wrong direction, do not flame me! (feedback is welcome!)