The first step of any piece is 2D research and composition work. Ideas, Sketches and an idea. After a idea forms I will often try and find a source image that matches the angle or design idea. 

If it's bespoke piece, usually I need just one accurate picture of the vehicle to work with, But this isn't always available as it might be a gift or it was a first car etc.

So I have to edit the spec of the vehicle to match grainy photos, memories or descriptions. To make sure the artwork is an exact match.