Infiniti's M45 Sport is one of those cars that made me rethink the definition of a sports car.

With a muscular, 335-horsepower V-8 stuffed under the hood and 19-inch wheels hanging on to the pavement like cat claws, the M45 Sport is easily as quick, and as nimble, as many two-seat sports cars. And you don't have to sacrifice a usable back seat and a nice-sized trunk to enjoy sports-car performance.

The M45 Sport has a base price of $49,550. Competitors include the BMW 5-series, Mercedes-Benz E-class, Lexus GS, Audi A6 and Acura RL.

For those who want the same look but don't need as much horsepower, the M35 is equipped with a 280-horsepower V-6 and starts at $40,640.

An all-wheel-drive M35 begins at $43,140. The V-8 is not offered with all-wheel drive. Infiniti's M models have a five-speed automatic transmission with manual shift mode, leather seats, voice recognition, keyless ignition, Bluetooth wireless technology, an in-dash six-disc CD changer and a power sunroof.

Infiniti's gutsy 4.5-liter V-8 is marvelously smooth, yet it flexes its muscles at the slightest urging. Nail the throttle and the engine responds with a muted howl.

Acceleration is strong and sure. Slip the automatic transmission into manual mode and shifting up and down through the gears is fun even if you're only running to the grocery store. The dual exhausts are loud enough to be stimulating, yet they don't interfere with the car's luxury persona.

The M model uses a modified version of the same FM chassis platform that is under the G35 sedan and FX crossover SUV. FM stands for Front-Midship, and that means the engine is located aft of the front wheel's centerline for more balanced weight distribution. The M45 Sport looks especially purposeful with a squat stance, big tires and a low roof. Short front and rear overhangs emphasize its performance character. The long wheelbase and short overhangs also contribute to a roomy interior, and the wide track adds stability. Aluminum is used for the hood, decklid and inner and outer door panels to save weight.

The M45's cabin has deep bucket seats that are firm and supportive. When they're equipped with the climate-control function, warm or cool air is circulated through the tiny perforations in the leather. I didn't find these seats to be as warm in the winter as regular heated seats, however.

Accessing and controlling the audio and climate systems is done via a large multipurpose knob on the dash, similar to BMW's iDrive system. The system is fairly intuitive, but it still requires time to understand which knob does what. Simpler would be better.

A 7-inch LCD display in the center of the dash contains readouts for heating/cooling, audio and the optional navigation system. The screen becomes a video monitor when the car is equipped with the rear-view monitor option. When the gear lever is put in reverse, the screen shows a video picture of the area behind the vehicle. The rear-view monitor is indispensable for parking because it has a movable grid pattern that shows just how close you are to objects behind the vehicle.

The M45 Sport does a great job of balancing ride comfort with handling. The ride never feels harsh, but the car remains uncommonly composed when you hustle it through turns. Rear-active steer uses electric motors to adjust the rear-wheel geometry to optimize stability. Electronic driving aids such as vehicle stability control, rear active steer, traction control, brake assist and anti-lock brakes also play an important role in maintaining agility and stability, especially in emergency evasive situations. The M sedan is available with a warning system that sounds an alert when the vehicle strays out of its lane.

Safety features include dual-stage front airbags and roof-mounted side-impact curtain airbags. The pre-crash option tightens front seat belts in anticipation of an evasive maneuver or a crash.



The base price of the test car was $49,550. Options included the Bose stereo, rearview monitor, XM satellite radio, pre-crash seatbelt system and a digital compass. The sticker price was $52,210.


Four years or 50,000 miles.


Engine: 4.5-liter, 335-hp V-8

Transmission: Automatic

Rear-wheel drive

Wheelbase: 114.2 inches

Curb weight: 3,995 lbs.

Base price: $49,550

As driven: $52,210

Mpg rating: 17 city, 23 hwy.


At A Glance

Point: The M45 Sport combines aggressive handling with a 335-horsepower V-8, luxurious cabin and a lean, athletic profile.

Counterpoint: The audio and climate control system is more complicated than it needs to be. The warm air that circulates through the seats is not as comfortable the warmth from electrically heated seats.

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