These are the concept art pieces of which I came up with for the two vehicles; rabies and Spanish flu. I feel that the two are different enough from each other so much so that they are both interesting in their own way, but still feel like they belong in the same universe.
I think that the red colour on both of the vehicles works well as it helps give them both unity. I went with the base red colour as it seemed fitting, as people associate the colour red with danger and blood, by using this colour it supports the fact that each of these viruses are deadly and targets humans for death.
In order to create the stylized pieces that are shown below, I went through the process of applying an under layer of colour that was picked straight from the microscopic images of the viruses themselves. This is how the orange and reddish pink colour was achieved. In terms of the foamy cloud erupting from the back of the vehicles (especially the rabies vehicle) the idea came from the symptoms of rabies, which of course is foaming at the mouth. To create the illusion of a thick foamy texture, I used a specific brush and use the overlay, soft light and colour dodge tools. Every time I painted this I would use different shades of white.
The idea behind the appearance of the Spanish flu came from the colours of the Spanish flag. By infusing the red and gold I felt that the vehicle would look better by adding a texture that would give a sense of deep red. This is to match the symptoms experienced by the victim of Spanish flu.