The steps in the below process from bottom to top are as follows

Step 1: After posing the model I start to trace in a bright color (easier to see)

Step2: After the tracing is done I'll stroke all the lines with a thicker line to make it stand out.

Step3: Without worrying about line thickness or detail I'll start to pick colors for the largest parts of the drawing.

Step4: Start to add detail and group lines and shapes together to make it easier to tame the image.

Step 5: Add lines that I'll use to define the movement in the piece. Because I want this illustration to seem like it was moving I used long sweeping lines that curled around the car.

The smoke was added to give the impression of a change of direction.

The composition was changed to allow more white space around the car.

Note, this is not finished. Thats all I'll do for now. Theres a lot of detail stuff that I'll pick up later after I've had a few days to look at it. All the little stuff I push back to the clean-up stage at the end of my deadline. For now this is a good start.