In an alternate universe, we're tearing through the blissfully serpentine asphalt twisting through Topanga Canyon outside of Los Angeles; a pull of the steering wheel paddle shifter drops the transmission into second before we enter a sweeping corner. Hard on the brakes, and then back into throttle to power out; we're now three-up in the new turbocharged 2011 Kia Optima SX, and quickly bearing down upon a BMW 5 Series. Sound like a dream? Hardly: the Optima SX hungrily devours challenging corners, and its turbocharged engine backs up its good looks with plenty of bite.

The 2011 Optima SX is part of an ongoing paradigm shift for Kia. Until very recently, the Korean automaker was content in building the blandest of transportation devices, designed neither to offend nor excite, and priced at bargain-basement levels. Now they're done with that. Over the past year, Kia has introduced disturbingly appealing vehicles at market-beating prices, and doing its best to shake its previously dodgy image. With the Optima SX, Kia has built a car that can legitimately vie for the title of best midsize family sedan on the market.

Let's not pretend about what we're looking at here. Since Hyundai and Kia are corporate bosom buddies, nearly all the hard parts and mechanical bits beneath the skin are shared with the also-new Hyundai Sonata Turbo. As is the case with the base Optima, the chassis features a McPherson strut front suspension, a multi-link setup in back, and a complete alphabet soup of stability aids. The top-of-the-line SX model receives upgraded 12.6-inch front discs, more aggressive damper tuning, and -- most importantly -- the all-new Theta Turbo GDI.

The 2.0-liter direct-injection, DOHC four-cylinder is blessed with both a 9.5:1 compression ratio and and forced induction, the latter provided by a clever new turbocharger package. The design integrates the exhaust manifold and turbo housing into one cast stainless steel piece, which feeds a ducted intercooler, and helps bring power up to 274 horsepower at 6000 rpm, and 269 lb-ft of torque starting at 1750 rpm. That's 74 horsepower and a hulking 86 lb-ft of torque over the base engine, but it's also the kind of power that justifies Hyundai/Kia's decision to ditch a V6 option. Paired only with a six-speed automatic transmission with shift paddles mounted on the steering wheel, the turbocharged Optima SX is expected to peg the 22/34 mpg (city/highway) mark, giving buyers the best of both worlds in terms of fuel economy and power.

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With two mechanically similar cars, what is Kia's value proposition? A European air in terms of chassis tuning, appearance, and feel. In place of the Sonata's swoopy, highly-styled sheet metal, the Optima's exterior is slab-sided, smooth and sleek. It wears Kia's corporate grille nicely, and the SX trim throws in a lowered front fascia and side skirts. Nineteen-inch machined face aluminum wheels add an upscale look to the car without overwhelming its proportions. There are neat details sprinkled around -- note, for instance, the top of the windshield, which mirrors both the shape of the grille and the slick LED taillights. The result is an honestly handsome sedan some could easily mistake as the latest Saab or Audi offering from afar.

Fittingly, the interior is less flamboyant more strapped down than its platform-mate and presents a refined, European aesthetic. Exceptionally high-quality materials run throughout, with soft touch plastics fitted in all the right places. The interior forms are more geometric in comparison to the Sonata's organic lines, but French-stitched seams around the instrument cluster and center stack, well-designed switchgear, and nicely finished seating surfaces delight. A navigation screen placed at the top of an angled center stack controls multimedia and phone integration, while buttons sorted beneath are tied to audio and climate control systems.

Owners may enjoy having these widgets present in the car, but they'll likely be more surprised by how good the Optima SX is to drive. Power comes on strong with no hint of turbo lag, and the transmission quickly finds the proper gear for rapid acceleration when you goose the throttle. In comparison to some of its V-6-powered competitors, the Optima's turbo-four feels slightly harsh, but that's the price paid for less weight and better fuel economy. Still, it's able to keep pace with six-cylinder cars in terms of acceleration. The Optima SX is downright quick, and we were floated an unofficial 0-60 mph time of roughly 6.5 seconds.

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You'd expect a chassis in this segment to protest the least bit of spirited driving, but that isn't the case. The Optima is quite composed, even when its suspension is unloaded in a tight corner. Ride quality is typical of the new Kia -- tuned for a more sporting feel and borderline stiff -- but aside from harsh impacts on nasty potholes, the car is quite comfortable. On-center feel is commendable and the electric power steering is tuned for just the right amount of feedback. Understeer only pops up at the limit of adhesion, but it appears in a predictable manner that inspires confidence.

As is often the case with front-wheel-drive cars packing big portions of power, putting all that grunt to the ground can be an issue. Kia has tuned the traction control software to carefully modulate torque during wheelslip, allowing the car to launch gracefully without the stereotypical wild wheel spin and awkward ignition cuts. Turn it off, however, and tire smoke and mild torque steer are entirely possible.

Perhaps most telling is our mindset after driving the Optima SX for an entire day. This is a 3,385-pound, four-door, five-passenger family sedan that stickers at $25,950, not a compact hot hatch designed to witness endless autocross abuse. Even so, it's as much fun to toss about as a smaller offering, and it's easy to forget just what Kia's true intentions are. We often found ourselves mulling quicker gearchanges or slightly more aggressive exhaust notes and suspension tuning, but this is by far one of the most engaging midsize sedans presently on the market.

The Optima SX isn't born from the Kia oft placed at the butt of automotive jokes for the last decade or so. Its mixture of speed, style, and sophistication is a quantum leap for the brand. If Kia covered this car's emblems, owners of upscale brands wouldn't hesitate to take a second look. If cars like this become the norm for the automaker, however, they won't have to hide that badge for much longer.