Maarten D. de Jong
Then it states if the next two spots are clear draw one material of choice (if both are empty draw 2 materials). Surely this is a typo and should mean draw one cube for one empty space, draw two for two empty spaces?
I'm not sure I understand your confusion. It means 'do what the open icon says you should do'. If one such image is open, you take one cube of choice. If in total two are open, you take in total two cubes of choice.
Then to the unclarity. Are the two slots additional to the random draw (as is the case with two other cars), or do these override the random draw so you get to choose rather than rely on chance?
No, they do not override anything. The rule is, as I indicated 'do what the open icon says you should do'; those icons are not modifiers.