This(指示代词作主语) is（系动词） called（被动语态,表语） forming a car pool.Men also form car pools,with后面是状语,其中three or four men 是taking turns的逻辑主语（因此此处不是一个完整的句子,只是一个非谓语动词作状语）;driving to the place 则是take的宾语,take turns doing sth;the place where they all work是定语从句,the place是先行词,where是关系副词,指代in the place,在从句中作状语