Roundabout

As far as I can tell, the location of the "regions" are random, so here are some hints to help out:

-Speed is important, but you shouldn't be wandering aimlessly. The radar can give you a great idea of where you need to go to find the next region. Even if you're at a 4 way intersection, going only slightly down the road can give you an idea of if you're starting to head in the wrong direction.

-Consider the shrink power-up. You need to have completed the game to unlock it, but it can help you weave your way around the obstacles very quickly and safely.

-RT for acceleration. When you start to get more comfortable with the area or find yourself in a fairly open road, you'll want to boost through it. I didn't feel comfortable with boost until much later in the game after I finished the speedrun challenge once or twice to get used to the idea of accelerating the majority of the time.

-Jump. Wait until you have this ability at least. Jumping, especially in the first area, can make it a simple task to get around the obstacles since there are less lights and posts that will impede your jump path. Use the accelerate to increase the distance of your jumps as well.

-Repair your limo. If you're passing a repair shop (purple or orange), consider stopping real quick and get the work done. The small repair could prevent the time loss for blowing up.

I was able to get 8 zones on my eventual finish. The goal is to try and keep calm even as your clock ticks down. You will lose a lot more time likely from crashing then you would from taking a section a little slower.