Infiniti Q50 Sedan Gets Steering Adjustment

Nissan Motor Co. is retuning the new adaptive steering system on its Infiniti Q50 flagship sedan billed as the first steer-by-wire system on a production car in response to criticism of the innovative technology during media previews.

The optional steering system on the 2014 model normally operates without a mechanical connection between the steering wheel and the steering rack. The system incorporates angular and force sensors that also provide reactive torque to the steering wheel, thus creating feedback felt by the driver. A rack-mounted electric motor steers the front wheels.

As a safety backup, a spring-loaded, solenoid-actuated clutch can engage a mechanical steering column in the event of a power failure or sensor glitch.

The system allows steering effort and the steering ratio to be adjusted independently at any time. In the Q50, the driver selects combinations of three ratios and three efforts with a pre-programmable mode that sets the combination favored by the driver.

Infiniti notes that the electronic response of the system is virtually instantaneous, compared to the inherent lag in a conventional power steering system caused by bushings, shaft windup, and other components. This also gives the driver immediate feedback and reduces the motion of the wheel during high-speed maneuvers or shallow highway curves.

But the distinctive feel of the system was disconcerting to some drivers, and Infiniti engineers responded by making minor tweaks. The new sport setup includes an optional package that uses different tires at the front and rear to slightly increase understeer.

The new Q50 also includes an optional lane-sensing system that tracks lanes using a forward-facing video camera. The technology automatically steers around shallow highway curves without turning the steering wheel.