I figured it out, just like sirensettings controls the lightbars, lightsettings controls all the vehicles exterior lighting (headlights, interior lights, taillights, reverse, etc)
You can actually specify those settings with an id value inside of the carcols file.
<Item>
<id value="75"/>
<indicator>
<intensity value="0.37500000"/>
<falloffMax value="2.50000000"/>
<falloffExponent value="8.00000000"/>
<innerConeAngle value="20.00000000"/>
<outerConeAngle value="50.00000000"/>
<emmissiveBoost value="false"/>
<color value="0xFFFF7300"/>
<textureName/>
<mirrorTexture value="true"/>
</indicator>
<rearIndicatorCorona>
<size value="0.00000000"/>
<size_far value="0.00000000"/>
<intensity value="0.00000000"/>
<intensity_far value="0.00000000"/>
<color value="0x00000000"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</rearIndicatorCorona>
<frontIndicatorCorona>
<size value="0.00000000"/>
<size_far value="0.00000000"/>
<intensity value="0.00000000"/>
<intensity_far value="0.00000000"/>
<color value="0x00000000"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</frontIndicatorCorona>
<tailLight>
<intensity value="0.25000000"/>
<falloffMax value="4.00000000"/>
<falloffExponent value="16.00000000"/>
<innerConeAngle value="45.00000000"/>
<outerConeAngle value="90.00000000"/>
<emmissiveBoost value="false"/>
<color value="0xFFFF0000"/>
<textureName/>
<mirrorTexture value="true"/>
</tailLight>
<tailLightCorona>
<size value="1.20000000"/>
<size_far value="2.50000000"/>
<intensity value="5.00000000"/>
<intensity_far value="1.00000000"/>
<color value="0xFFFF0F05"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</tailLightCorona>
<tailLightMiddleCorona>
<size value="0.00000000"/>
<size_far value="0.00000000"/>
<intensity value="0.00000000"/>
<intensity_far value="0.00000000"/>
<color value="0x00000000"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</tailLightMiddleCorona>
<headLight>
<intensity value="1.50000000"/>
<falloffMax value="35.00000000"/>
<falloffExponent value="16.00000000"/>
<innerConeAngle value="0.00000000"/>
<outerConeAngle value="60.00000000"/>
<emmissiveBoost value="false"/>
<color value="0xFF7FA7E3"/>
<textureName>VehicleLight_car_LED1</textureName>
<mirrorTexture value="false"/>
</headLight>
<headLightCorona>
<size value="0.10000000"/>
<size_far value="7.00000000"/>
<intensity value="7.00000000"/>
<intensity_far value="5.00000000"/>
<color value="0xFF61A5FF"/>
<numCoronas value="2"/>
<distBetweenCoronas value="32"/>
<distBetweenCoronas_far value="68"/>
<xRotation value="0.00000000"/>
<yRotation value="0.18221200"/>
<zRotation value="0.58433600"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</headLightCorona>
<reversingLight>
<intensity value="0.50000000"/>
<falloffMax value="7.20000000"/>
<falloffExponent value="32.00000000"/>
<innerConeAngle value="20.00000000"/>
<outerConeAngle value="78.00000000"/>
<emmissiveBoost value="false"/>
<color value="0xFFFFFFFF"/>
<textureName/>
<mirrorTexture value="true"/>
</reversingLight>
<reversingLightCorona>
<size value="0.80000000"/>
<size_far value="2.00000000"/>
<intensity value="1.50000000"/>
<intensity_far value="1.00000000"/>
<color value="0x00F7F7F7"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</reversingLightCorona>
<name>fugitive</name>
</Item>
There's an example, the fugitive has lightsettings 75!
So if you apply lightsettings="75" in carvariations, to any vehicle, it will use those settings. (theoretically)
CARCOLS.YMT
<Item>
<id value="3"/>
<indicator>
<intensity value="0.37500000"/>
<falloffMax value="2.50000000"/>
<falloffExponent value="8.00000000"/>
<innerConeAngle value="30.00000000"/>
<outerConeAngle value="80.00000000"/>
<emmissiveBoost value="false"/>
<color value="0xFFFF8000"/>
<textureName/>
<mirrorTexture value="true"/>
</indicator>
<rearIndicatorCorona>
<size value="0.00000000"/>
<size_far value="0.00000000"/>
<intensity value="0.00000000"/>
<intensity_far value="0.00000000"/>
<color value="0x00000000"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</rearIndicatorCorona>
<frontIndicatorCorona>
<size value="0.00000000"/>
<size_far value="0.00000000"/>
<intensity value="0.00000000"/>
<intensity_far value="0.00000000"/>
<color value="0x00000000"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</frontIndicatorCorona>
<tailLight>
<intensity value="1.00000000"/>
<falloffMax value="4.00000000"/>
<falloffExponent value="8.00000000"/>
<innerConeAngle value="45.00000000"/>
<outerConeAngle value="90.00000000"/>
<emmissiveBoost value="false"/>
<color value="0xFFFF0000"/>
<textureName/>
<mirrorTexture value="true"/>
</tailLight>
<tailLightCorona>
<size value="0.15000000"/>
<size_far value="0.75000000"/>
<intensity value="1.00000000"/>
<intensity_far value="5.00000000"/>
<color value="0xFFFF1A00"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</tailLightCorona>
<tailLightMiddleCorona>
<size value="0.00000000"/>
<size_far value="0.00000000"/>
<intensity value="0.00000000"/>
<intensity_far value="0.00000000"/>
<color value="0x00000000"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</tailLightMiddleCorona>
<headLight>
<intensity value="4.00000000"/>
<falloffMax value="40.00000000"/>
<falloffExponent value="160.00000000"/>
<innerConeAngle value="15.00000000"/>
<outerConeAngle value="70.00000000"/>
<emmissiveBoost value="false"/>
<color value="0xFFFFE894"/>
<textureName>VehicleLight_misc_searchlight</textureName>
<mirrorTexture value="false"/>
</headLight>
<headLightCorona>
<size value="8.00000000"/>
<size_far value="1.80000000"/>
<intensity value="2.80000000"/>
<intensity_far value="10.00000000"/>
<color value="0xFFFFFFFF"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</headLightCorona>
<reversingLight>
<intensity value="0.50000000"/>
<falloffMax value="4.00000000"/>
<falloffExponent value="32.00000000"/>
<innerConeAngle value="45.00000000"/>
<outerConeAngle value="90.00000000"/>
<emmissiveBoost value="false"/>
<color value="0xFFFFFFFF"/>
<textureName/>
<mirrorTexture value="true"/>
</reversingLight>
<reversingLightCorona>
<size value="0.80000000"/>
<size_far value="2.00000000"/>
<intensity value="1.50000000"/>
<intensity_far value="1.00000000"/>
<color value="0x00F7F7F7"/>
<numCoronas value="1"/>
<distBetweenCoronas value="128"/>
<distBetweenCoronas_far value="255"/>
<xRotation value="0.00000000"/>
<yRotation value="0.00000000"/>
<zRotation value="0.00000000"/>
<zBias value="0.25000000"/>
<pullCoronaIn value="false"/>
</reversingLightCorona>
<name>Submersible</name>
CARVARIATIONS.META
<variationData>
<Item>
<modelName>submersible2</modelName>
<colors>
<Item>
<indices content="char_array">
132
0
122
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 />
<windowsWithExposedEdges />
<plateProbabilities>
<Probabilities />
</plateProbabilities>
<lightSettings value="3" />
<sirenSettings value="0" />
</Item>
Submersible2 [Lightsettings=3]