I finished the file for ya....
I got a little carried away and added more stuff than i needed to, but feel free to use any thing i added in the file.
What i have done is that i fake the steering-wheel with invisible controls. So if you touch left or right on the steering-wheel the car will turn.
In the demo below i have also added keyboard controls so that you can test withour a touchdevice. Use the Arrow-keys to steer, gas and brake.
Playtest the demo here:
Download the .capx file from here: