@inbetweendays_ exactly as @ReNNie says, you need to change the value of maxNumOfSameColor line to whatever suits your need but also you should take a look at the carvariations.meta file to see how many color variations are defined for that car.The line in carvariations.meta shoul look like this:
<modelName>turismo2</modelName>
<colors>
<Item>
<indices content="char_array">
29
40
87
112
93
93
</indices>
and so it goes.Those numbers you see represent a certain color in game.
Let's say for our case you want to spawn Turismo Classic and for example if there is only 87 in that indices no other numbers but just 87.In this case, the game controls first carvariations.meta and sees that 87 which simply tells the game Turismo Classic will only be spawned with color code 87.But if you try to add any number between 0-255 then the game takes also consideration of maxNumOfSameColor value and spawn as many cars as possible with many color combos.
Hope this will make things clear and easier for you.