Where Cadillac was once the envy of the world, it now finds itself struggling to compete with it. Models like the CTS-V and ATS have captured the attention of younger buyers, but the company must also balance the needs of its older, wealthier customer base. That's where the 2015 Cadillac XTS luxury-performance sedan comes into play. Although not as large as an Audi A8, the XTS nevertheless is Cadillac's flagship vehicle, demonstrating the razor-sharp styling that has become the company's hallmark. If there is an Achilles heel in the XTS' design, it's the somewhat complex CUE information and entertainment system. Still, when placed side-by-side with the Lexus GS, Mercedes-Benz E-Class and even the BMW 5 Series, the XTS proves a worthy competitor.