The Infiniti FX45 offers comparable acceleration performance to the Porsche Cayenne S, according to each manufacturer's statistics. Infiniti says the FX45 can zip from 0 to 60 mph in slightly more than 6 seconds, while Porsche says the Cayenne S takes nearly 0.2 second longer. How can that be? Though Porsche's V8 engine is more powerful, the Infiniti FX is considerable lighter, so each of its 315 horses must haul fewer pounds.
The V6-powered FX35 is no slouch, either. It launches impressively from a stop, largely because it has substantially more horsepower and torque than most other six-cylinder SUVs. There's as much oomph here as most owners will ever need. We found its acceleration performance entirely satisfactory.
Granted, the step up to the V8 is noticeable, particularly when you stab the gas at, say, 60 mph. The FX45 will rocket to 80 at a much greater rate than the FX35. Yet the V8 also chugs fuel at a much greater rate, reducing range anywhere from 25 to 75 miles per tank, according to the EPA's numbers. Both FX models are electronically limited to a top speed of 130.
All this power is managed with sophisticated electronics with names that sound like alphabet soup. The ATTESA E-TS (Advanced Total Traction Engineering System for All Electronic Torque Split) provides outstanding cornering capability due to its optimum 50/50 front/rear torque distribution, which can shift rearward up to 0/100 when conditions require. The system provides good starting traction and stable acceleration in snow-covered or off-road situations, since it always starts off with the torque split 50/50.
The VDC electronic stability control system reduces engine output and/or lightly applies braking force to individual wheels when entering a corner too fast. It engages so gradually that we couldn't detect when it was working.
The FX suspension reflects Infiniti's decision not to make this SUV an off-road vehicle. Off-road ability is enhanced by long travel and compliant suspension tuning, but those same characteristics compromises handling on smooth, winding roads. The FX is tuned for those winding roads. Despite its 7.6 inches of ground clearance, it has no skid plates or underside armor, and the up-down range of movement at its wheels is limited compared to most SUVs.
In tight and sweeping corners alike, the body stays incredibly level, which is the plus side of its stiff suspension. We drove it hard, like we would a sports sedan. Understeer, or the sliding of the front tires that is the default skid condition in most vehicles, begins very gradually when you aim the FX into a corner, and the front wheels continue to push only slightly until you get near its very high cornering limits. When driven hard, the VDC allows a slight amount of power oversteer while cornering (a satisfying fish-tail effect in the rear), although we were never able to break the mammoth rear tires completely loose. As in the 350Z, the FX's steering is quick. It doesn't feel as telepathic as a Porsche's, but it doesn't feel light and loose like that in many SUVs, either.
The brakes are good. The FX45 remains confident and stable under heavy braking, and that allowed us to drive it very quickly, without any scary moments, on twisty roads. Yet there is unquestionably a lot of mass underneath, and it needs to be slowed down. A vehicle as heavy as the FX, but also as nimble, can require acute awareness from the driver, because it feels so well-mannered that it's easy to forget how fast it's going and how heavy it is. The best brakes and most sophisticated stability electronics devised can not defy the laws of physics.
Still, the FX offers a new braking trick that until recently was reserved for the most expensive luxury sedans. Called Preview Braking, it comes on FXs equipped with the traffic-sensing Intelligent Cruise Control system. The radar sensors that manage the active cruise control can sense when the FX is closing on an object at a high rate. When they do, the system pre-pressurizes the brake hydraulics before the driver even touches the pedal; that speeds brake activation by critical fractions of a second once the driver's foot and the pedal meet.
The FX45 can be as much fun to drive as many sport sedans, but the payback is a stiff ride. On the typical stretch of freeway, it isn't a problem. There the FX45 rides smoothly enough, and it feels relaxed. It cruises at 80 mph in fifth gear with the engine turning a low, quiet 2800 rpm. The cabin is quiet and isolated enough for delicate cell phone conversations, but it's not the serene environment of a true luxury sedan.
The FX35 without the sport package rides more smoothly and more pleasantly. It's still plenty nimble and quick, and fun to drive. But its suspension is slightly more compliant, more comfortable in most situations, and its higher profile tires take some of the crack out of bumps and expansion joints. However, even the FX35's suspension is on the firm side and the ride gets a little bumpy on rough streets at low speeds.
The new Lane Departure Warning system, which comes bundled with the DVD entertainment package ($1,750) recognizes lane markings through a small camera mounted behind the rearview mirror. Above 45 mph, a microprocessor uses the camera's signal and the vehicle's speed to calculate both the distance between the FX and the lane markings, and the lateral velocity at which those markings are getting closer. The system sounds a buzzer if it decides that the vehicle is wandering out of its lane. The system is temporarily disabled by the turn signals, and it can beshut off entirely with a manual cancel switch. It automatically resets itself when the vehicle is restarted. Next Page