afaik this only happens in mayas viewport. you can export collada models in quads, but when the models are packed to engine data they get triangulated, its not done in real time (seems like thatd be a waste of resources?). ive never heard of an engine flipping quad edges in real time
@hardware - I don't think it's necessarily the file size they would be worried about. It's more the size (in pixels) of the texture. Most engines end up taking all the textures of all objects in the scene and indexing them together into one big texture sheet. The fewer textures you use, and the smaller they are, the easier…