okay I found a C-script workshop at GameStudio Wiki... Gonna have a look at it tomorrow.

For now I must ask what could be wrong with my prefab of a piece of street. The textures aren't even nearly where i put them before saving as prefab (I also texture locked them before save)and I can't even run the level because I get error which says one of the textures is bad sized... (36x256)

I think it would be easier to make levels with working prefabs