Sometimes it’s hard to anticipate the car’s curves and angles when you’re looking a two-dimensional image on the screen.
Most of the time, it helps to look at the car in person and take notes on the possible problem areas.
Bring a print-out of the vehicle. Take measurements. Circle the problem areas and scribble notes in the margin. The more information you can gather, the easier it becomes to identify the space that you have available in your artwork.
If you don’t have access to the car in person, grab pictures with google image search of the car and take quick notes on the different views of the car.
The best practice to help your design translate well when it’s applied to the car in the end is to keep important text and images away from the edges and allow plenty of extra bleed space at the edges of the artwork. If the text runs to the edge of the car, you risk cutting off important pieces of information.
Another thing that people find challenging when beginning to design a vehicle wrap is the question of composition. The lines and curves of the car interfere with the standard grids of composition.
Try following the body lines of the car and lining up the text elements with the windows.