Following the concept’s debut at April’s New York auto show, Acura unveils the production version of its new RLX flagship sedan today at the 2012 Los Angeles auto show.

Billed as “the most powerful, spacious, and technologically advanced Acura sedan ever,” the midsize RLX replaces the 8-year-old RL sedan and the soon-to-be-discontinued ZDX cross/utility vehicle as Acura’s flagship model.

The RLX’s length is similar to the RL but adds 2 ins. (5 cm) to the RL’s wheelbase and overall width. Acura claims the car has more rear legroom than the BMW 535i, Lexus GS 460 and Audi A6.

On sale in the spring, the RLX introduces many new technologies to Acura, including the brand’s first direct-injected V-6 engine, a 310-hp 3.5L that is paired with parent Honda’s cylinder deactivation technology.

Honda calls for more than 90% of the mill’s peak torque of 272 lb.-ft. (369 Nm) to be made from 2,000-6,600 rpm.

RLXs fitted with the new DI mill are expected to achieve a best-in-class fuel economy of 20/31 mpg (11.8-7.6 L/100 km) city/highway, or 24 mpg (9.8 L/100 km) combined.

A revised version of Acura’s 6-speed automatic transmission is standard, as are paddle shifters.

Another powertrain, a 370-hp hybrid unit mated to Acura’s Super-Handling All-Wheel Drive technology, debuts later next year. It is projected to achieve fuel economy of 30 mpg (7.8 L/100 km) city, highway and combined.

All-new for Acura is Precision All-Wheel Steer, which combines with the stability and traction controls to continuously and independently adjust the left and right rear-wheel steering toe angles for better agility and maneuverability, the auto maker says.

The RLX also will have a variety of advanced safety technologies, including adaptive cruise control and lane-keeping assist.

Cap-less fueling is another Acura-first debuting on the car.

The exterior design features a “wide and athletic stance,” dressed up with Jewel-Eye light-emitting diode headlights and 7-spoke 18- or 19-in. aluminum-alloy wheels.

Inside the RLX, Acura employs premium Milano perforated leather, two center stack screens – one dedicated solely to navigation, the other audio and climate controls – and an optional “ultra-premium” Krell audio system.

Acura has not released sales expectations for the RLX. The RL reached its peak in 2005 with 17,572 units sold, WardsAuto data shows, while ZDX deliveries topped out at only 3,259 units in 2010.

cschweinsberg@wardsauto.com