@Lundy I only found one color setting in the readme:
<Item>
<modelName>stanier</modelName>
<colors>
<Item>
<indices content="char_array">
134
0
0
156
</indices>
<liveries>
<Item value="false" />
<Item value="false" />
<Item value="false" />
<Item value="false" />
<Item value="false" />
<Item value="false" />
<Item value="false" />
<Item value="false" />
</liveries>
</Item>
</colors>
<kits>
<Item>0_default_modkit</Item>
</kits>
<windowsWithExposedEdges />
<plateProbabilities>
<Probabilities>
<Item>
<Name>police guv plate</Name>
<Value value="100" />
</Item>
</Probabilities>
</plateProbabilities>
<lightSettings value="77" />
<sirenSettings value="0" />
</Item>

And here is mine what i made:
<Item>
<modelName>stanier</modelName>
<colors>
<Item>
<indices content="char_array">
134
11
0
156
</indices>
</Item>
<Item>
<indices content="char_array">
8
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
23
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
31
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
48
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
64
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
103
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
105
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
143
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
107
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
126
11
0
120
</indices>
</Item>
<Item>
<indices content="char_array">
74
11
0
120
</indices>
</Item>
</colors>
<kits>
<Item>0_default_modkit</Item>
</kits>
<windowsWithExposedEdges />
<plateProbabilities>
<Probabilities>
<Item>
<Name>Standard White</Name>
<Value value="40" />
</Item>
<Item>
<Name>Blue Plate</Name>
<Value value="20" />
</Item>
<Item>
<Name>White Plate 2</Name>
<Value value="30" />
</Item>
</Probabilities>
</plateProbabilities>
<lightSettings value="77" />
<sirenSettings value="0" />
</Item>

Corrected the plates too, your settings make the car spawn with the 'ca exempt' plate.