The never adhered to the German model of tight-handling saloonry. Instead, its territory is the budget-conscious middle between beige Japanese technobarges and the rear-drive sedan Buick wishes it had the balls to build. Now Hyundai's created a sharper version with a more powerful engine. But is it a true performance sedan?

Hyundai wanted us to drive the Genesis 5.0 R-Spec so badly they flew me to Las Vegas, put me up in a swank-but-casinoless hotel (thankfully), and brought in Don Felder, former guitarist of the Eagles, to ensure his solo from "One Of These Nights" remained fully burned into my memory core.

I'm traveling across Nevada's Valley of Fire State Park in the Genesis 5.0 R-Spec, whose 429 horses bubble up from a new five-liter version of Hyundai's Tau V8. It's a well-considered engine, stroked from the company's 4.6-liter Tau, then re-intaked and direct-injected. The five-liter, which Hyundai will offer as an option on the top-line Equus sedan, also has electronic throttle control, consigning the old bowden cable to the Museum of Perfectly Good 19th Century Bicycle Technologies.

Outside it's 111°F, according to the nav screen, up from 109°F a minute ago. The AC's blaring out "Song of the 737s in F# Minor" against the intensifying desert heat. About 50 miles northeast of Las Vegas, Route 147 shows off its recent pave, courtesy of Uncle Sam. "Lake Mead Boulevard," as 147's known, is as smooth as a Luther Vandross album cut, and begs for someone to defile it with rubber frags.

So, down goes the pedal on the large Korean sedan with the new engine.

The good news, at least for buyers who enjoy smooth power delivery, is, well, it's smooth. The bad news? Despite the R branding, the new engine isn't the assertive type. It's not the high-revving screamer you hoped would one day show up in the Genesis Coupe for hunting Mustang GTs. It's a luxury engine, more befitting the Equus.

But it's no slouch; Hyundai says the 4,100-pound R-Spec can get from 0-60 in 5.1 seconds. When the pedal's planted, speed accrues like compound interest on the as-tested price of $46,535.

The engine can indeed do work. More than 300 lb-ft of its 376 lb-ft peak torque is available at 1,500 rpm. Power output is an impressive 85 hp/liter — impressive for a luxury car. But a true performance variant should reach a little further toward the 100 hp/liter mark.

The R-Spec isn't entirely about the engine, though. Chassis tuning plays a significant role. Fortunately, my driving partner on this desert burn is Wendell Collins, lead chassis engineer, who explains the goal was to make incremental tweaks that would retain the sedan's character, not to make it the fastest Genesis through a gymkhana course. Performance-wise, the point is to keep it flatter in corners and to turn in more accurately.

Those tweaks include a 19 mm hollow rear stabilizer bar and stiffer springs at the front and rear, and higher damping rates applied to the Genesis sedan's usual Sachs ASD gas shocks.

Route 147, which mainly comprises long sweepers, isn't giving us a read on the chassis's fortitude for tighter cornering. Still, in high-speed turns it conveys the pillowy feel of the base V8 sedan, and yet stays flat. Roll remains modest when it's forced into an impromptu slalom. The electro-hydraulic steering carries largely over from the base V8 model, but it's been calibrated to service the larger 19" wheels. While slightly weightier and more precise, the sensations are more remote than I'd prefer for attacking a canyon road.

The new eight-speed transmission, which [UPDATE: Hyundai designed and manufactured in-house], stays low in the mix, doing its business without causing trouble. This is a tranny built for economy (note its skip-shift feature) and luxury, however; its Speedshift capability works well for holding gears, though a more rigorous test on switchback might yield other results. Nonetheless, the eight-ratio box is built for smooth, and smoothness is where it most excels. Starting to see a pattern here?

Granted, the Tau V8 and mild suspension tweaks doesn't make the Genesis an M5 beater. But it does provide a good advance platform on which to test out the higher-spec Tau's veracity ahead of use in other products, like the Equus. Naturally, we'd prefer they hold off on the performance badging until they built a proper performance car.

Not that you'd know it's a higher-spec model from the interior. Hyundai's diverged from those import factory tuners, whose badges deck out every seat back and dashboard surface like graffiti tags. Look down, however, and you might spot the R-Spec badge on the floormats.

Ultimately for drivers, the Genesis R-Spec is the automotive equivalent to upgrading your razor from three blades to five. It does the job just a little bit better, it's faster and smoother, you're out just a bit more money and maybe you smile a little wider when you pick it up in the morning. "Yeah, five blades," you think. "Nice."