Open the MAS file of an installed mod using the gMotor2 MAS file utility. Find the *.veh file you want to use, note down the name. When creating your vMod, you need a custom RFM. Remember to save your edited RFM elsewhere but keep a copy in your %userprofile%\AppData\Roaming\~MASTEMP folder. Once you create your vMod, the rfm you made will disappear. Here I merged the Howston's with a WTCC BMW