Groups or layers in material panel?

Hi! I imagine this has probably been asked before but I could not find anything. Is it possible to add anything to help keep materials organized, IE adding some to a collapsible sublayer or group etc?

Sometimes when importing several files like cars etc, you can end up with 100 randomly named textures. Which makes it hard to keep track of and assign the materials you care about, it would be nice to have all those in one collapsible item etc.