police5.yft, police5.ytd, police5_hi.yft, and police5+hi.ytd go here:
Grand Theft Auto V\update\x64\dlcpacks\mpchristmas2\dlc.rpf\x64\levels\gta5\vehicles\xmas2vehicles.rpf

CARVARIATIONS.META--------------------------------------------------
Grand Theft Auto V\update\update.rpf\dlc_patch\mpchristmas2\common\data
INSERT THIS CODE UNDERNEATH <variationData> NEAR THE TOP OF THE FILE

	<Item>
      <modelName>police5</modelName>
      <colors>
        <Item>
          <indices content="char_array">
            134 
            134 
            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 />
      <windowsWithExposedEdges />
      <plateProbabilities>
        <Probabilities>
          <Item>
            <Name>police guv plate</Name>
            <Value value="100" />
          </Item>
        </Probabilities>
      </plateProbabilities>
      <lightSettings value="39"/>
      <sirenSettings value="5" />
    </Item>

VEHICLES.META--------------------------------------------------
Grand Theft Auto V\update\update.rpf\dlc_patch\mpchristmas2\common\data\levels\gta5
INSERT THIS CODE UNDERNEATH <InitDatas> NEAR THE TOP OF THE FILE

    <Item>
      <modelName>police5</modelName>
      <txdName>police5</txdName>
      <handlingId>POLICEOL2</handlingId>
      <gameName>POLICEO2</gameName>
      <vehicleMakeName />
      <expressionDictName>null</expressionDictName>
      <expressionName>null</expressionName>
      <animConvRoofDictName>null</animConvRoofDictName>
      <animConvRoofName>null</animConvRoofName>
      <animConvRoofWindowsAffected />
      <ptfxAssetName>null</ptfxAssetName>
      <audioNameHash>policeold2</audioNameHash>
      <layout>LAYOUT_STANDARD</layout>
      <coverBoundOffsets>POLICEOLD2_COVER_OFFSET_INFO</coverBoundOffsets>
      <explosionInfo>EXPLOSION_INFO_DEFAULT</explosionInfo>
      <scenarioLayout />
      <cameraName>DEFAULT_FOLLOW_VEHICLE_CAMERA</cameraName>
      <aimCameraName>DEFAULT_THIRD_PERSON_VEHICLE_AIM_CAMERA</aimCameraName>
      <bonnetCameraName>VEHICLE_BONNET_CAMERA_MID_HIGH</bonnetCameraName>
      <povCameraName>DEFAULT_POV_CAMERA</povCameraName>
      <FirstPersonDriveByIKOffset x="0.000000" y="-0.025000" z="-0.015000" />
      <FirstPersonDriveByUnarmedIKOffset x="0.000000" y="0.000000" z="-0.020000" />
	  <FirstPersonProjectileDriveByIKOffset x="0.040000" y="-0.095000" z="0.000000" />
	  <FirstPersonProjectileDriveByPassengerIKOffset x="0.040000" y="-0.095000" z="0.000000" />
	  <FirstPersonProjectileDriveByRearLeftIKOffset x="0.000000" y="0.020000" z="0.010000" />
	  <FirstPersonProjectileDriveByRearRightIKOffset x="0.000000" y="0.020000" z="0.010000" />
	  <FirstPersonDriveByLeftPassengerIKOffset x="0.000000" y="0.000000" z="0.000000" />
	  <FirstPersonDriveByRightPassengerIKOffset x="0.000000" y="-0.025000" z="-0.015000" />
	  <FirstPersonDriveByRightRearPassengerIKOffset x="0.000000" y="0.000000" z="0.000000" />
	  <FirstPersonDriveByLeftPassengerUnarmedIKOffset x="0.000000" y="0.000000" z="0.000000" />
	  <FirstPersonDriveByRightPassengerUnarmedIKOffset x="0.000000" y="0.000000" z="0.000000" />
	  <FirstPersonMobilePhoneOffset x="0.155000" y="0.166000" z="0.503000" />
      <FirstPersonPassengerMobilePhoneOffset x="0.136000" y="0.113000" z="0.395000" />
	  <FirstPersonMobilePhoneSeatIKOffset>
		<Item>
			<Offset x="0.136000" y="0.066000" z="0.415000" />
			<SeatIndex value="2" />
		</Item>
		<Item>
			<Offset x="0.136000" y="0.066000" z="0.415000" />
			<SeatIndex value="3" />
		</Item>
	  </FirstPersonMobilePhoneSeatIKOffset> 
      <PovCameraOffset x="0.000000" y="-0.250000" z="0.630000" />
      <PovCameraVerticalAdjustmentForRollCage value="0.000000" />
      <PovPassengerCameraOffset x="0.000000" y="0.000000" z="0.000000" />
      <PovRearPassengerCameraOffset x="0.000000" y="0.050000" z="0.015000" />
      <vfxInfoName>VFXVEHICLEINFO_CAR_GENERIC</vfxInfoName>
      <shouldUseCinematicViewMode value="true" />
      <shouldCameraTransitionOnClimbUpDown value="false" />
      <shouldCameraIgnoreExiting value="false" />
      <AllowPretendOccupants value="true" />
      <AllowJoyriding value="false" />
      <AllowSundayDriving value="false" />
      <AllowBodyColorMapping value="true" />
      <wheelScale value="0.209300" />
      <wheelScaleRear value="0.209300" />
      <dirtLevelMin value="0.000000" />
      <dirtLevelMax value="1.000000" />
      <envEffScaleMin value="0.800000" />
      <envEffScaleMax value="1.000000" />
      <envEffScaleMin2 value="0.800000" />
      <envEffScaleMax2 value="1.000000" />
      <damageMapScale value="0.600000" />
      <damageOffsetScale value="1.000000" />
      <diffuseTint value="0x00FFFFFF" />
      <steerWheelMult value="1.000000" />
      <HDTextureDist value="5.000000" />
      <lodDistances content="float_array">
        15.000000
        30.000000
        70.000000
        140.000000
        500.000000
        500.000000
      </lodDistances>
      <minSeatHeight value="0.843" />
      <identicalModelSpawnDistance value="20" />
      <maxNumOfSameColor value="10" />
      <defaultBodyHealth value="1000.000000" />
      <pretendOccupantsScale value="1.000000" />
      <visibleSpawnDistScale value="1.000000" />
      <trackerPathWidth value="2.000000" />
      <weaponForceMult value="1.000000" />
      <frequency value="100" />
      <swankness>SWANKNESS_1</swankness>
      <maxNum value="999" />
      <flags>FLAG_HAS_LIVERY FLAG_LAW_ENFORCEMENT FLAG_EMERGENCY_SERVICE FLAG_NO_RESPRAY FLAG_HAS_INTERIOR_EXTRAS FLAG_REPORT_CRIME_IF_STANDING_ON</flags>
      <type>VEHICLE_TYPE_CAR</type>
      <plateType>VPT_FRONT_AND_BACK_PLATES</plateType>
	  <dashboardType>VDT_DUKES</dashboardType>
      <vehicleClass>VC_EMERGENCY</vehicleClass>
      <wheelType>VWT_SPORT</wheelType>
      <trailers />
      <additionalTrailers />
      <drivers>
        <Item>
          <driverName>S_M_Y_Cop_01</driverName>
          <npcName />
        </Item>
      </drivers>
      <extraIncludes />
      <doorsWithCollisionWhenClosed />
      <driveableDoors />
      <bumpersNeedToCollideWithMap value="false" />
      <needsRopeTexture value="false" />
      <requiredExtras />
      <rewards>
        <Item>REWARD_WEAPON_PUMPSHOTGUN</Item>
        <Item>REWARD_AMMO_PUMPSHOTGUN_ENTER_VEHICLE</Item>
        <Item>REWARD_STAT_WEAPON</Item>
      </rewards>
      <cinematicPartCamera />
      <NmBraceOverrideSet />
      <buoyancySphereOffset x="0.000000" y="0.000000" z="0.000000" />
      <buoyancySphereSizeScale value="1.000000" />
      <pOverrideRagdollThreshold type="NULL" />
	  <firstPersonDrivebyData>
        <Item>STD_POLICEOLD2_FRONT_LEFT</Item>
        <Item>STD_POLICEOLD2_FRONT_RIGHT</Item>
        <Item>STD_POLICE2_REAR_LEFT</Item>
        <Item>STD_POLICE2_REAR_RIGHT</Item>
      </firstPersonDrivebyData>
    </Item>

VEHICLES.META CONTINUED --------------------------------------------------
INSERT THIS CODE UNDERNEATH <txdRelationships> NEAR THE BOTTOM OF THE FILE

    <Item>
      <parent>vehicles_monroe_interior</parent>
      <child>police5</child>
    </Item>