The Good: Elegant design; climate-controlled seats; useful tech interface; driver-adaptive transmission; MP3 CD and WMA support. The Bad: No navigation on our test car. The Bottom Line: The Infiniti M35x is a fine example of useful, nongratuitous high-tech luxury. 2006 Infiniti M35xInfiniti claims the 2006 M35 is its most technologically advanced car to date, and looking at its mechanical and especially electronic specs, we can't disagree. The sports-luxury-class M35 is powered by a 280-horsepower, 3.5-liter V-6. Most M35 models use a rear-wheel-drive architecture, but our test car, the 2006 Infiniti M35x, was an all-wheel-drive (AWD) model. That AWD system is meant for sporty performance as much as all-weather traction--it was developed from the one used in the legendary Nissan Skyline GT-R. Rear-drive models come in Luxury and Sport specifications, with Sport versions featuring Rear Active Steer, a computer-controlled, variable active-rear-suspension geometry that changes to assist steering depending on steering input and vehicle speed. The 2006 Infiniti M35x has a base price of $43,140. Our test car was equipped conservatively with only the Journey Package, which includes a Bose two-channel, eight-speaker audio-system upgrade, climate-controlled front seats, the HomeLink universal transmitter, the RearView monitor, automatic-leveling Xenon HID headlamps, front precrash seat belts, and a compass in the inside rearview mirror for $2,750. Add a $610 destination charge for a total of $46,500. Much more is available: We recommend the Technology Package, which adds the nav system; a Bose surround-sound 5.1 audio system; intelligent cruise-control and lane-departure systems; and your choice of XM or Sirius satellite radio for an additional $4,200. But even without the extras, the M35x is a pleasant, sporty, and roomy luxury sedan with all-weather ability.The 2006 Infiniti M35x, like all Infiniti M models, uses an Intelligent Key transponder instead of a regular key for access, with push-button starting, and is Bluetooth-enabled for hands-free cell phone operation. Anything that can be power-operated is, and it is simple for drivers of any size to find the combination of seat and steering-wheel positions for optimum comfort. With a 4-inch increase in wheelbase compared with the G35's, the 2006 Infiniti M35x's interior is comfortably spacious, with very good head and knee room in the front and rear. The perforated leather covering the front and outboard rear-seating surfaces is good for more than looks, since, with the Journey Package, it hides the workings of the climate-control seat system in front. Cabin air is drawn in from under the seat, then passes through a thermoelectric heating and cooling element in the seat back before being fan-forced through passageways in the foam and out through the ventilation holes. The cooling effect is pleasantly comfortable on a hot summer day. The seats themselves provide the comfort and support we expect in a luxury car.The Infiniti M35x's electronics are easily accessed from the rotary controller.The instrument panel has two centers of attention--the four-gauge main instrument cluster, enhanced by its orange-backlit Solar Eclipse lighting scheme, as well as the centrally mounted controls for the audio, climate, and information systems. These are controlled through well-marked buttons and the rotary controller or by voice, with information displayed on an LCD screen. Control is simple, logical, and mostly intuitive, with high marks to the voice-recognition system for ease of use. Unfortunately, the screen is not well protected from glare and can be hard to see in some light. The 2006 Infiniti M35x's audio system has MP3 CD and WMA playback capability. The upgraded Bose two-channel, eight-speaker system that is part of the Journey Package produces fine-quality sound, which is adjusted automatically to compensate for ambient noise. Another part of the Journey Package is the RearView system. It improves upon earlier backup video systems in that the wide-angle display is overlaid by colored dashed lines, which indicate an area that's the width of the car, as well as solid lines that display the car's projected trajectory and are calculated by the amount of steering lock. It is much more useful than systems that merely display the area behind the car, given that the straight, wide-angle perspective is confusing when you compare it to a normal visual perspective.The 2006 Infiniti M35x's DOHC 24-valve, aluminum-alloy, VQ35 V-6 engine uses continuously variable-valve timing on its intake camshafts to produce 280 horsepower at 6,200rpm, with 270 pound-feet of torque at 4,800rpm. The five-speed automatic transmission is electronically controlled and can adapt its shifting to the driver's driving style. It does a good job in most situations, not always going for the highest possible gear and almost making manual-shift mode unnecessary--almost. Manual shifting is, at times, more rewarding, and usually results in quicker acceleration, since gears can be held as long as possible. And the M35x, even with a couple hundred extra pounds for the AWD system, is quick enough to be satisfying. EPA fuel economy is 17mpg in the city and 24mpg on the highway; we averaged 18 in mixed driving. In the 2006 Infiniti M35x, power gets to all four wheels through the ATTESA E-TS AWD system, which is also used in some G35 and FX models. With roots in the Nissan Skyline GT-R, this full-time system is designed for performance as much as all-weather traction and helps the M35x make the best use of its power. The torque split varies between full rear drive and 50-50. Interestingly, considering driven front wheels usually result in a wider turning circle, the M35x's turning radius is slightly less than that of the rear-wheel-drive models. Also, its electrically controlled, speed-sensitive power steering has a slightly quicker ratio. The steering is never too light, and its response is very good. The Infiniti M35x's automatic transmission adapts to the driver's style.The 2006 Infiniti M35x's double-wishbone front and multilink rear-suspension systems make extensive use of aluminum to reduce unsprung weight and improve handling. Aluminum is also used for the door, hood, and trunk panels to reduce overall weight. Springs and shocks are tuned in the manner of a European sports sedan, supple enough for comfort, yet firm enough for minimal body roll and very good road manners. For a car on the large end of midsize, the M35x is light on its feet and very satisfying to drive in a sporty manner. As with the G35, careful attention to underbody airflow gives the M35x a low coefficient of aerodynamic drag (0.28) with zero front lift.Standard safety equipment on the 2006 Infiniti M35x includes a unibody structure built with front and rear crumple zones; the Advanced Air Bag System, which features dual-stage front air bags with Occupant Classification and roof-mounted side-impact curtains; a direct-reading tire-pressure-monitoring system; and four-wheel, ventilated antilock disc brakes with EBD (electronic brake force distribution) and brake assist. The VDC stability-control system also comes with all models, and unusually for a luxury car, it can be switched off for more aggressive driving. Optional equipment includes precrash front safety belts, which tighten under braking in preparation for an evasive maneuver or a crash; laser-based lane departure and intelligent-cruise-control systems; preview braking, which works with the brake assist and intelligent-cruise-control systems to detect situations that may require immediate braking and, if so, prepressurizes the brake system for quicker response; adaptive front lighting, which moves the headlights in response to steering; and the RearView backup system. A space-saver spare tire is standard, but a full-size spare is available.The 2006 Infiniti M35x is covered by a four-year\/60,000-mile basic warranty, with six-year\/70,000-mile limited power train coverage and seven-year unlimited-mileage corrosion coverage.