Good old foam core work model - Not used very often in the movie business, but this model validated the concept. The director saw it and within a few seconds he said it was fine. Good way to "feel"the prop and see the actuel proportions.
Deathrace: Mustang interior - Based on this concept illustration, the interior was built. Due to time restrictions, not every element was drawn up. Mixture on collage and illustration. Here we see with the ejection seat