Sector-defining?<p>The medium sporting saloon was fairly well established in Europe by the time the E21 arrived.  Alfa Romeo, Lancia and Triumph were well established in the mainstream and there were plenty of smaller specialists too.<p>BMW came along with a well-screwed-together package and struck marketing gold with that famous tag-line even though other cars may have been technically superior.  That iPhone analogy is looking pretty accurate.<p>Anyway the 3-series today has little heritage with That original vision.  The E36 Compact ( which actually used parts of the E30 chassis ) was probably the last of that lineage until the recent 1-series.