So whenever I place say one of BxBugs123's Whelen Talons inside the car in Zmodeler then go and test it in game ELS doesn't work but if I leave the Talon on the outside of the car it works fine? This has been really bugging me!

Make a duplicate of your window material. This button==>

Then there will be another vehglass material all down your material list. Assign the windows where you can't see the Whelen trough to that vehglass material you made a copy of!

I can see the Talon in Game just not its ELS 

I can see the Talon in Game just not its ELS 

 

If doing what compeast said didn't work, try moving the extras above the windows in the hierarchy.

If doing what compeast said didn't work, try moving the extras above the windows in the hierarchy.

THANK YOU SO MUCH!