Again, this is not a trick, just something about a different approach in playing the game.

I was wondering if it is possible to jump over the barriers in Blue City. Maybe some secret road is on the other side!!!!
So I picked up my fastest car and hit the barrier at max speed with about 45° angle.
Well, now I know there are no secret roads (and it's good that there are no possible shortcuts or something). There is just the big empty.... so it's probably not that interesting, anyway, here are the first pics of Blue City prohibited zones 

Here I passed throught the barrel at the end of the straight

If they are intended to block the way....These yellow things are completely useless 

Finally, this is new road! A road walked only by me!! It sounds cool 

DOH!! My cool road lasts only a few meters 

The Big Empty!!!! 

Then, I jump over the barriers near the finish line (I still miss the one in the opposite direction). Look at the upper right... can you see the actual track? We should see the tarmac, but it's invisible from this viewing angle 

Again, a few meters of road and then...

The Big Empty!!!!

Final shots: well, things start getting pretty psychedelic when you decide to jump down  (or when it happens that you simply bounce onto the barrier and fall off the track.... Blue City is actually a giant overbridge so there is no off road! If you exit the track, you' re lost in space and time lol!!!!