Designed by the man who helped craft the NSX suspension and who formerly worked on Honda's Formula 1 race team, the new, standard Precision All-Wheel Steer (P-AWS) system makes the RLX feel as if it's directly dialed in with the driver.
Also notable: Combined city/highway fuel economy for the RLX is more than 24 miles per gallon and bests Infiniti, Lexus, Mercedes-Benz and BMW competitors.
The RLX's direct injection V-6 comes standard with Variable Cylinder Management that automatically deactivates some engine cylinders when they're not needed, thus saving gasoline.
Though it has the same overall length as the midsize RL, the RLX has surprisingly generous rear-seat legroom – 38.8 inches – which surpasses that in the Infiniti M and Mercedes E-Class sedans.
In addition, the RLX offers new safety features, including a system that gently steers the car back into its lane if it detects wandering over the center line. This works only if there is a lane marking that is detectable by the system.
Meantime, adaptive cruise control with Slow Speed Follow can bring the car to a full stop in certain circumstances if the RLX is headed for the rear-end of a stopped vehicle in front of it.
But the RLX, like its RL predecessor, is front-wheel drive, rather than the rear-wheel drive that some sporty luxury sedan purists prefer.
Starting manufacturer's suggested retail price is up only $250 from its predecessor Acura RL.
Other standard equipment includes leather-trimmed seats and stitched leather instrument panel cover, moonroof, push-button start, keyless entry, three-zone climate control, Acura/ELS premium audio system with 10 speakers, Bluetooth connectivity, two sizable display screens in the dashboard and a rearview camera.
Buyers can move up through four trim levels to add navigation, lane keeping, a new Krell audio system with 14 speakers, sunshades and ventilated seats.
While the federal government fuel economy ratings for the RLX are 20/31 mpg for city/highway travel, the midsize M37 is rated at 18/26 mpg.
The interior of the top-of-the-line RLX with Advance package was top-notch in fit and finish, with small gaps between trim pieces and everything lined up perfectly.
This RLX included additional acoustic glass that helped keep the interior so quiet, front-seat passengers conversed in light tones.
P-AWS wasn't noticeable until the driver went around a curve at good speed and discovered how stably – maybe the word is magically – the 16-foot-long RLX tracked through.
The system provides more stable handling on slippery surfaces, too.
The most fascinating aspect during the test drive, perhaps, was how little the steering wheel had to be turned to keep the car on track in the curves and how balanced the sizable RLX felt.
Indeed, on mountain switchback roads, the RLX remained firmly planted and was so tenacious, its back-and-forth motions from one curve to the next created some carsickness for the driver.
The lasting impression: How the RLX molds itself to the driver's capabilities and habits, rather than forcing the driver to learn the car.
It's true the 3.5-liter V-6 is single overhead cam and only produces 310 horses and 272 foot-pounds of torque at 4,500 rpm. This is less than what many competitors deliver. But the RLX is some 160 pounds lighter than its predecessor RL, and the test RLX felt plenty powerful, even if power delivery wasn't race-car instantaneous.
Unleaded premium is the recommended fuel, so a fillup of the 18.5-gallon tank these days could cost more than $72.
Then again, with an average of 24.3 mpg during the test drive on mostly country roads and some highway travel, the RLX's range on a single tank was a good 450 miles.
The sweeping design of the dashboard away from passengers gave an airy feel to the interior.
But seat cushions could be a tad longer to better accommodate long-legged passengers, and the two display screens take some getting used to.
There are no 2013 RLs as the RLX is arriving now in showrooms as an early 2014 model.
Later this calendar year, Acura will introduce a gasoline-electric "sport" hybrid version of the RLX that promises to generate more than 370 horsepower.