For years, buyers searching for a fast, 4-door performance sedan were limited to the usual suspects from BMW M, Mercedes-AMG, and Audi RS. With Alfa Romeo finally back in the US, enthusiasts can now pick up the incredibly well balanced Giulia sport sedan and this Quadrifoglio high performance model powered by a twin-turbo Ferrari V6 with over 500 horses should put a formidable dent in all of its German competitor's armor.