for 1$ you get extra cars in game no unlocked cars
for 5$ you get all default cars (no extra) unlocked
We are right now working hard on update that should be out already, but It was hard to manage time properly.
It is really hard to give any estimate on when update will be, but it will be soon.
As for cheats. Cheats are there to unlock special cars that can not be unlocked in any other way. Right now there are 2 cars that can be unlocked like this. We would like to extend this to more.
PS: Hint for cheat code: Combine some keys like you do sometimes on your PC :-)
PPS: Comment here if you want more hints, but it should be easy to figure out.