[Acid]

For each vehicle you want to make burn when destroyed like the Dragon Tank you need to go to the code of that vehicle in the FactionUnit.ini file located in Data\INI\Object and find the SlowDeathBehavior and change the FX = FINAL line. Here's an example of the SlowDeathBehavior for the Crusader tank:

  Behavior = SlowDeathBehavior ModuleTag_10
    DeathTypes = ALL -CRUSHED -SPLATTED
    ProbabilityModifier  = 50
    DestructionDelay  = 500
    DestructionDelayVariance  = 100
    FX  = INITIAL  FX_GenericTankDeathEffect
    OCL = MIDPOINT OCL_GenericTankDeathEffect
    FX  = FINAL    FX_GenericTankDeathExplosion
    OCL = FINAL    OCL_CrusaderTurret
  End

Replace FX_GenericTankDeathExplosion with FX_DragonTankDeathExplosionFinal so that the code looks like this:

  Behavior = SlowDeathBehavior ModuleTag_10
    DeathTypes = ALL -CRUSHED -SPLATTED
    ProbabilityModifier  = 50
    DestructionDelay  = 500
    DestructionDelayVariance  = 100
    FX  = INITIAL  FX_GenericTankDeathEffect
    OCL = MIDPOINT OCL_GenericTankDeathEffect
    FX  = FINAL    FX_DragonTankDeathExplosionFinal
    OCL = FINAL    OCL_CrusaderTurret
  End

The code will vary for different units but you will always change the same line. Repeat this for every vehicle you want to add the burning wreckage effect to.
Now you want to do is search for the term "dead" in order to find the dead hull objects for each vehicle. Every vehicle has one. the first one i think is for the Humvee which and is listed as Object AmericaVehicleHumveeDeadHull you cant find everything by searching for "DeadHull" as other vehicles have different ones, some are "DeadHulk" for example, but they all contain the term dead. Now for each unit that is on fire when it dies you want to change the LifetimeUpdate to this:

  Behavior = LifetimeUpdate ModuleTag_04
    MinLifetime = 0 ; min lifetime in msec
    MaxLifetime = 0 ; max lifetime in msec
  End

And then change the SlowDeathBehaviour to this:

  Behavior = SlowDeathBehavior ModuleTag_05
    SinkDelay = 14000
    SinkRate = 2 ; in Dist/Sec
    DestructionDelay = 20000
  End

Repeat this for the wreckage of every vehicle you have added the burning effect to and then you're done.