Habemus Papem! Like the installation of Francis, the world’s first Latin American pontiff, the crowning of a Lexus as the high priest of the sports-sedan world is something few saw coming—until we dove into the twisting, climbing, kinking, plunging roads around Leakey, Texas.

We didn’t see it coming because, on any other type of road, the IS clearly exhibits Lexus’s traditional top priority: serenity. On typical highway surfaces, minute twitches in the steering wheel and nearly imperceptible shifts of the body offer only the slightest hint of what lurks within. But charge into a series of quick bends and the IS completely changes its character. Turn-in is crisper in the Lexus than in either the BMW or the Cadillac, a fact borne out by its first-place slalom finish in spite of a mediocre skidpad performance. More important, the Lexus is utterly imperturbable. Bumps that send other cars skittering off-line or scrambling to maintain their course are absorbed and dispatched, but not kept completely hidden from the driver.

It used to be that, in this class, there was a clear divide in terms of refinement between the BMW inline-six and the engines offered by competitors. That gap is rapidly shrinking. Both the Cadillac’s and the Lexus’s Vs are surprisingly close to the BMW straight-six, but the IS’s is smoother than the ATS’s. And its eight-speed automatic is quicker and more seamless than the Caddy’s six-speed though basically on par with BMW’s transmission.

Additionally, the Lexus is lavishly, indulgently comfortable. Its front seats are an ergonomic feat, perfectly cupped and padded with no tangible break between back and bottom cushions, just one immaculate sweep of support from shoulders to thighs. Our drivers, trapped within a wide array of body types, unanimously swooned. Yes, the BMW is slightly more spacious in the rear, but nobody anywhere in that car is as comfortable as the people in the front of the Lexus. It’s a good thing we have so few other complaints about the IS, though, because its mouse-operated infotainment system burns through our good will in short order and turns us into sputtering, apoplectic maniacs. “Distracted driving” is a rallying cry for safety advocates everywhere; this device is infotainment’s nadir, a deserving flashpoint for a revolution against its kind.

Every other negative gets turned around when you wake the IS up, though. Its variable-ratio steering, seemingly overboosted and a touch slow in highway travel, comes alive on coursing two-lanes, quickening and taking on a pleasing heft. The brake pedal feels a tad touchy when commuting, but reacts more predictably under duress, better coordinating pressure to stopping power. The IS manages to be both typically Lexus-civil and delightfully capable (its stops are still the longest, though). Roman Catholicism preaches transubstantiation, the belief that consecrated bread and wine become flesh and blood. The manner in which the Lexus transforms from innocuous to vivid is nearly as miraculous.

On the tight circuit, the IS' chassis demeanor and ultimate grip far exceed its predecessor's. There's minimal body roll in the stiffest Sport S+ mode, and it plows only when prodded extremely hard.

This third-generation IS nails its fun to drive assignment. Its design is fresh (albeit controversial); its cabin technologically packed and roomy (you'll easily fit a 6-foot 2-inch passenger in the back, and with the new 60/40 split rear seats, luggage will fit, too); and its chassis and powertrain are as buttoned-down as they come.

The most performance-minded enthusiasts may pine for a manual gearbox. Yet, this lack of a three-pedal option doesn't negate the fact that the IS has enough grip, grunt, and gravitas to satisfy the sport-minded, luxury-loving masses, and quite possibly, outshine its German and Michigander adversaries.