The M45 is available with Infiniti's Lane Departure Warning system. LDW alerts drivers to pending, unintended lane departures by recognizing lane markings and calculating the distance between the vehicle and the marking, as well as the car's speed.
Infiniti's 4.5-liter V-8 in the M45 is rated at 325 horsepower. The engine drives a five-speed automatic transmission that features a manual-shift mode.
The M45 comes with rear-wheel drive, while the M35 version comes with rear- or all-wheel drive. A Rear Active Steer system on the M45 Sport model adjusts the geometry of the rear according to steering input and car speed and features motor-driven control.
The M45 is built on Infiniti's FM platform, which is also used for the G35 coupe and sedan and FX sport utility vehicles. Wide front and rear tracks are intended to enhance stability. The front fenders and hood are sculpted, and L-shaped LED taillamps and quad tailpipes bring up the rear. Lightweight body components include aluminum-alloy inner and outer door, hood and deck-lid panels. A power-sliding sunroof is standard, and a rear spoiler is optional.
Each M sedan is 192.6 inches long overall and 70.8 inches wide; a 114.2-inch wheelbase is used. The Sport edition gets 19-inch tires and a sport-tuned suspension. Standard tires are 18 inches.
Climate-controlled seats are standard on the M45 and M45 Sport models for 2007.
The M45 can seat up to five. The interior features leather-appointed seats and wood or aluminum trim. The driver faces a "solar eclipse" instrument lighting system. Standard equipment includes an Intelligent Key with push-button start, voice recognition, Bluetooth wireless connectivity, an in-dash six-CD changer with MP3 playback capability, a 10-way power driver's seat and a Vehicle Information System with a 7-inch LCD screen. The Sport model adds aluminum trim accents.
Heated, power-reclining rear seats and a 14-speaker Bose Studio Surround system that plays 5.1-channel DVD audio discs are available.
Options include Intelligent Cruise Control and a DVD-based navigation system with voice-activated destination entry. The optional backseat video entertainment system uses an 8-inch roof-mounted screen.
For 2007, a technology package bundles the Bose audio system and DVD video/audio drive along with Intelligent Cruise Control.
Under the Hood
The M45's 4.5-liter V-8 develops 325 hp and 336 pounds-feet of torque. The V-8 mates with a five-speed automatic transmission.
All-disc antilock brakes with electronic brake-force distribution and brake assist, seat-mounted side-impact airbags, side curtain airbags, Infiniti's Vehicle Dynamic Control stability system and a tire pressure monitoring system are standard. Brake-operated pre-crash front seat belts, which tighten under emergency braking in anticipation of a crash or an evasive maneuver, are available. A RearView monitor with a wheel-trajectory view is optional. For 2007, the M45 gets auto-leveling and adaptive xenon headlights that shine in the direction of a turn.
The Sport edition of the M45 is fitted with a taut suspension. Even though the ride isn't bad on smooth surfaces, you'll feel its firmness.
The M45 copes easily with moderate curves. The solid steering feel is somewhat on the heavy side, but it's precise. Acceleration is vigorous, but not breathtaking. Automatic-transmission responses are quick, but the gearshift lever is unusually short. Stomping on the accelerator produces some exhaust snarl, and you're soon moving faster than expected thanks to the smooth powertrain.
Visibility is good in all directions, but wide B-pillars can impair the view a bit. Large controls atop the center stack are well marked. Deep-set orange-lit gauges are easy to read. Solid cupholders are useful, and the analog clock adds an elegant touch.
The superior seats have firm support and ample cushioning. Snug bolsters aren't overly intrusive, but the ones in the Sport model are more confining than those in the regular M45.