My Audi 5's wind up pretty tight and are pretty smooth. Better than a 4, not quite as smooth as a 6. Have a nice unique exhaust note too.
Subarus' flat four always sound like they're idling on only 3 cylinders when the exhaust system starts getting a bit loud. Kinda wierd. First time I heard it, I thought it was just particular that car with a prob, but since then, every one I've heard sounds the same.