The only tracks you can't drive on are the snow and dirt tracks. I'm guessing if you unlock all of the tires for the kart you should be able to take it anywhere, that allowed me to take a BMW (with no dirt tires available) on a dirt track.
I've been meaning to try the karts on dirt, but I'm guessing they will just bounce and spin all over the place.
Kiddys ;-(
Its a very needfull think to drive a cart on each track ;-((
I hope with 1000000 HP not lower is allowed.
Paint it green like a frog then it will work after you have reached 900mph on one of the cart tracks.
:evil::evil::evil::evil:
Other possibillity is to take your PS3 in a car drive 250mph in speedlimitzone from 35mph for 10min.
Then drive home and it will work too.
:kiss::kiss::kiss::kiss: