Normally, as a minimum, you just need to add a new *.veh file to add a new team.
So i don't know now if you have taken all williams files and made a copy as "modded" files and if you did edit e.g. the gen files too.
In your *.modded.veh file you have the entry "GenString=MO119" but i don't think that you have created a new MAS-file which contains the matching gmt.
That is the reason for your error-messages.
Make it more simple to start.
Take the following code and paste it into the modded.veh file. Put this file into the williams folder then, where the williams_19.veh file is.
Now the car should show up in Menu and you can modify it with it's own texture and other things and/or create a new folder for it, for a better overview.. But always be sure, that the files that you list in the *.veh file are present and in the listed folder.
And the entries in all files have to match to existing things.
Test-Code for new Team/Car:
Code:
DefaultLivery="Williams_19/Williams_19.dds"
HDVehicle=F12015_Physics.hdv
Graphics=Williams_Graphics.gen
Spinner=Williams_Spinner.gen
Upgrades=Williams_Upgrades.ini
GenString=WI19
Cameras=Williams_Cams.cam
Sounds=Williams_Sounds.sfx
HeadPhysics=F12015_HeadPhysics.ini
Cockpit=Williams_CockpitInfo.ini
BaseVehiclePrice=0
UnlockExperience=0
Number=56
Team="#56 Modded F1 Team"
PitGroup="Group10"
Driver="Jules Bianchi"
Description="#56 - Jules Bianchi"
ChassisName="MO56"
Manufacturer="Modded"
Engine="Mercedes PU106B Hybrid"
FuelBrand="Petrobras"
TyresBrand="Pirelli"
Classes="F12015PAT, Modded"
FullTeamName="Modded F1 Team"
Base="Grove, UK"
TeamPrincipal="Peter Sauber"
TechnicalChief="Mika Corksman"
FirstSeason="2015"
Races="0"
DriversTitles="0"
TeamTitles="0"
HighestRaceFinish="0 (x114)"
PolePositions="0"
FastestLaps="0"
Category="F1 2015"
[RFETire]
RFETireCompat = 1 // Enable RFETire visual changes for this vehicle.
RFETireGMTCount = 1 // Every compound will have xxx GMT files.
RFETireGMTLOD0 = 0.0f // LODIN of first gmt.
RFETireGMTLOD1 = 600.0f // LODOUT of first gmt AND LODIN of second gmt.
RFETireGMTLODOut = 10000.0f // LODIN for GMT files of non-selected compounds.
