Infiniti’s M is a blend of high performance, great handling, slick styling and a plush interior. There are five models of three versions — the V-8 M45, the M35, and all-wheel drive (AWD) M35X — our test vehicle.

The new M is a serious sports sedan threatening such upscale competitors as the Jaguar S-Type, BMW 5-Series, Lexus GS, Mercedes-Benz E-Class, Acura RL, Audi A6, and Cadillac STS. With the exception of its premium G35, that’s a market Infiniti has had difficulty penetrating — until now.

Walkaround: The new M has the same stylish lines as the full-size Q45, although it has an even has a longer wheelbase — 114.2 inches compared to 113 inches for the “Q.” But the M is also 8.2 inches shorter than the Q, with short front and rear overhangs that give it an aggressive, sporty, look aided by wide front and rear tracks.

Interior: The more powerful M offers a higher level of luxurious refinement and higher-quality interior materials than the G35. The entire M lineup features leather upholstery, sunroof, power tilt-telescoping steering wheel and a large number of power and comfort-convenience features, all standard. The interior is trimmed in tasteful rosewood, while the sport versions boast aluminum trim.

The posh interior is very roomy, easily accommodating four adults. The middle rear seat is uncomfortable for a fifth person, and is best utilized as a spot to flip down the large armrest, which features sturdy cupholders. The Sport version also has heated and cooled sport seats that provide excellent support.

Infiniti’s (and parent Nissan) signature amber-lit instrumentation is easily readable at a glance and the backlit gauges don’t allow bright sunlight to wash them out. Controls are generally simple and easy to figure out and use. The large inside rearview mirror and thick lower windshield posts partially obscure vision under some driving conditions, and it’s almost impossible to see directly behind the car when backing up. However, the dashboard-mounted screen for the optional navigation system does double duty with the available rearview camera to solve that problem.

Voice control is standard for some audio and climate functions, and hands-free, Bluetooth is available for wireless phones. An AM/FM/6-disc CD audio system with MP3 and WMA playback capabilities, along with your choice of XM or Sirius satellite radio, is standard. Our test model was equipped with the optional, kick-ass, 14-speaker, Bose Studio Surround system and XM.

The standard “intelligent key” system eliminates using the key fob to lock or unlock the car, open the trunk — or start the engine. That’s accomplished by putting your foot on the brake and pushing the dashboard-mounted “Start” button — which also shuts down the engine as well as has an accessory setting.

Additional options include an audible warning for unintended lane departures, and a cruise control system that maintains an adjustable, set distance from a vehicle ahead, as well as a heated power reclining rear seat. There’s also a rear DVD entertainment system to keep kids entertained.

Under The Hood: Strong performance across the full M model spectrum is delivered by dual overhead cam, multi-valve powerplants. The 3.5-liter, 24-valve, V6 in the M35X puts 275 ponies to the pavement with 268 ft. lbs of torque. This is basically the same engine powering Nissan’s awesome 350Z, tuned specifically for this car. It’s been universally recognized as one of the best, most versatile and dependable powerplants since the small-block Chevy and Cadillac NorthStar.

The smooth, sophisticated V6 works seamlessly with a responsive 5-speed automatic transmission that has a manual shift mode with downshift rev matching that works exceptionally well.

The M35X is the only M equipped with Infiniti’s advanced all-wheel-drive system. It has a balanced front-rear driving feel and, depending on the trim level, 18- or 19-inch wheels. Our test model had the 8-spoke, aluminum alloy 18-inchers. There’s also a Rear Active Steer system available that steers the rear wheels slightly for better handling.

Behind The Wheel: I had the opportunity to put the M35X through its paces on a trip to Ocean Shores and back, which included some exceptionally stormy weather over twisting two-lane blacktops. I had also driven it previously over the mountains between Lake Roosevelt and Scottsdale, Arizona, which offered a complete contrast of terrain and driving conditions.

The all-independent suspension provides a ride that is comfortable, but firm, and coupled with the constantly working AWD system, keeps the M35X firmly planted on the road. Weighing in at just under 4,000 pounds, the M35X feels lighter than it actually is, and I found the quick, precise steering to be nicely weighted — especially on the highway. Powerful 4-wheel disc brakes have an easily modulated pedal, brake assist, and electronic brake force distribution for short, panic stops.

Standard safety items on all Ms include anti-lock brakes, anti-skid/traction control, front-seat side airbags and head-protecting side-curtain airbags.

Premium fuel is required, with the AWD M35X V6 rated at 17 mpg/city and 24/ highway.

Whines: The large trunk has a rather high, short opening that’s somewhat inconvenient during quick cargo loading and unloading. But the strut-mounted lid pops up high and prevents accidental head-banging. While the interior is generally quiet, the 19-inch tires are a bit noisy on some roads, with mild wind noise at highway speeds.

Bottom Line: Infiniti has had difficulty being perceived as prestigious a brand as Lexus, BMW, Jaguar or Mercedes. But the entire M model lineup is sleek, luxurious, fast and solid, demanding long overdue respect by openly challenging the world’s most prestigious sports-luxury sedans on their own turf. Frankly, the AWD M35X is a car I personally would enjoy owning — more than any of its competitors.