What is an Infiniti? That's a pretty harsh question to be asking 20 years after the brand's debut, but sadly, it's pertinent. To be fair, the possible answers to this question got much narrower in 2003 when Infiniti introduced a legitimate BMW 3 Series competitor, the G35 (now G37). The situation further clarified that same year when the "Bionic Cheetah," known to the rest of us as the FX showed its (then) quite handsome face. But it was the 2005 introduction of the second generation M sedan that announced most loudly Infiniti's luxury-performance aspirations: to kick BMW in the back of the pants.