Ok, I found really fast and easy way how to fix transparent textures bug (windows, textures with alpha)
It's really simple
Let's start, take Ambulance as example
1. import ambulan.dff to ZM2, you see there is transparent texture bug
2. delete all model (see screen)
3. open Material Editor, delete materials only with "trans" flag and materials with transparent textures, leave all other materials (see screens)
4. now import ambulan.dff back
5. done. now you can edit this car and export with no transparency bug
This works for all vehicles