Nissan Motor Co. Ltd.’s Infiniti luxury division of late has climbed from the ranks of the also-rans to a legitimate luxury contender, on the strength of its G35 sports sedan and FX 35/45 cross/utility vehicle.

But while its popular vehicles have sent sales skyrocketing, its flagship Q45 and M45 sedans have been languishing. Infiniti at the New York auto show is laying the groundwork to remedy problems at the top of its lineup.

Marking its world debut is Infiniti’s M45 concept, which a spokesperson calls close to the production car that will bow in about a year as an ’06 model. The concept sports the luxury brand’s future design and technology direction – which includes a choice of two engine variants, the option of all-wheel drive and either a sportier or more luxury-oriented direction.

Infiniti’s M45 concept car.

“The M45 Concept is an expression of the power, refinement, technology and style – all the things that make Infiniti owners’ hearts pound,” says Mark Igo, vice president and general manager-Infiniti Div.

The design is meant to capture both the feeling of luxury and of sportiness, featuring a low and aggressive hoodline that flows into a sporty, powerful silhouette. Large wheels, high-performance tires and short overhangs emphasize a stable, performance-driven posture, while a “jewel-like” grille and “crystal-look” headlamps are meant to create an aura of luxury. That theme is carried into the interior, which Igo says “reflects a more passionate interior direction, which is already starting to appear in production Infiniti vehicles.”

The concept capitalizes on some of the best features of the G35 and FX – both from the FM platform. Some 60% of the platform design and components have been enhanced for use with the M45 concept. Changes were made to accommodate either of the M45’s engine variants: the 4.5L 340-hp DOHC V-8, also used in the Q45 flagship, or the 3.5L V-6 used in the G35 and in many of Nissan’s sportier models.

The concept’s engine is mated to a 5-speed automatic transmission with a short-throw performance shifter with manual shift mode. It also sports an advanced braking system, vehicle dynamic control and a new active rear control system.

This new system features motor-driven rear-wheel control to improve handling performance by adjusting the geometry of the rear suspension according to steering input and vehicle speed. The concept’s suspension is an independent double-wishbone design in front and a multi-link independent in the rear.

Revamped Infiniti Q45 debuts.

The M45 Concept also features Infiniti’s new lane-departure warning system. The system recognizes lane markings and calculates the lateral distance between the vehicle and marking, along with vehicle speed relative to the marking, and generates a sound to warn the driver of a possible, unintended lane departure. The system, canceled by the turn signal, also includes a switch for the driver to turn it off.

Infiniti at the New York show also is taking the wraps off a freshened version of its top-of-the-line Q45, which has suffered from dismal sales.

Changes to the front end are meant to appeal to a broader audience. A redesigned grille, hood and headlights, and new integrated fog lamps are striving for a more aggressive appearance. In the rear, Infiniti made changes to the fascia, bumper, trunk lid and taillights, while adding fine-line chrome trim to accentuate the entire exterior.

The interior also benefits from enhancements, including new sport-contour, double-stitched seats, redesigned meter and control clusters with soft-touch finish to the controls, and enhanced trim.

A spokesperson would not say if the new Q45 is supposed to significantly increase volumes (Infiniti only sold 2,440 units last year), but he adds that while sales have been down, transaction prices on the Q45 steadily have grown – and now are up $10,000 per vehicle from previous levels.

The facelifted Q45 reaches dealers in July as an ’05 model.