Overview & Reviews

Though high-end vehicles now come in more shapes and sizes than ever, the midsize luxury sedan segment remains the heart of the luxury automobile market. Nissan's luxury division, Infiniti, has been around since 1990, yet it had no real presence in this key segment until 2003, when the V8-powered, rear-wheel-drive M45 was launched. Although it offered a credible amount of luxury and performance, the original M45's relatively uninspired design and cramped interior kept it from registering anything more than a faint blip on luxury buyers' radar screens.

The last iteration of the Infiniti M45, however, enjoyed wide critical acclaim. With substantially more space, a tremendous amount of technology and comfort features, and a bold, imposing exterior design, the last M45 was a high-tech powerhouse with plenty to offer midsize luxury car shoppers. Its performance capabilities were raised significantly due to things like available four-wheel steering, a precisely tuned suspension and strong brakes. Even though the V6-powered M35 represented a significantly better value and offered potent performance, the current M45 was a swift, stylish, superbly executed luxury sedan that should be considered with the contemporary top players in the segment.

The M45 was replaced by the redesigned M56 for the 2011 model year.

Most Recent Infiniti M45

The most recent generation of the Infiniti M45 was produced from 2006 to 2010. First-year models were listed as having 335 horsepower, with subsequent models rated at 325 hp. This was due to a change in horsepower measurement rather than actual output and thus, performance was unaffected. The M45's five-speed automatic transmission had manual-shift control and a sporty rev-matching feature that imparted a particularly lively feel to downshifts.

Originally, there were two trim levels: base and Sport. Even the base car included such items as leather upholstery, driver memory functions and dual-zone automatic climate control. Stepping up to the Sport netted you 19-inch wheels, a sport-tuned suspension, active rear steering and adaptive xenon headlights. Options included such high-tech fare as navigation adaptive cruise control, lane-departure warning system and a surround sound system.

For '08, the mildly face-lifted M45 gained the option of all-wheel drive and its M45x AWD trim level. The Sport trim was also replaced that year in favor of an optional Sport package on rear-drive base models, while the navigation system was given a welcome overhaul that included a hard drive and digital music storage. It remained unchanged before making way for the redesigned M56.

The Infiniti M45's interior was well appointed and well built, with firm seats that were highly adjustable, comfortable and heavily bolstered. However, the competition in this segment was pretty intense and the M35 wasn't quite as elegant and thoughtfully engineered as some of its rivals. The quality of materials was a bit uneven, and we found that the layout of the center stack controls wasn't as clean and intuitive as it could be.

In road test reviews, editors praised the Infiniti M45 for its explosive power, sharp handling and its bounty of luxury features. Criticisms of the M45 included overly intrusive road noise and complicated center-stack controls that were hard to master. Also, we questioned the logic of buying the thirstier V8, when the M35's V6 provided nearly as much power.

Past Infiniti M45 models

The first-generation Infiniti M45 was sold for 2003 and '04 -- there was no 2005 model -- and was basically a Japanese-market Nissan Cedric luxury sedan brought over to fill the gap between Infiniti's near-luxury G35 and the larger, technology-laden Q45. Engineered for the narrow streets of Japan, the M45's cabin proved too narrow to hold corn-fed Americans comfortably, and the backseat was scant on legroom for a car of its size. Even worse, the M's exterior design was bland to a fault.

However, it was fast. The original M45 was available only with a 340-hp V8 and rear-wheel drive. Combined with big 18-inch wheels and performance tires, the M45 delivered respectable handling. Equally important, the original M45 was equipped with nearly the same number of safety features as today's model.

Cheaply priced and available with most of the luxury features found on the larger Q45, first-generation M45s generally represent strong used-car values in terms of feature content and performance. For shoppers who like the car's combination of stealthy speed and luxury, and don't need a lot in the way of interior room, the first-generation Infiniti M45 could be a good match.

User Reviews:

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  BWM Beater - 2006 Infiniti M45
  By David - December 27 - 4:03 am

  Most BANG for the buck. Techno car for all. Performance and handling and comfort all in one package that is reliable

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  Excellent Car - 2007 Infiniti M45
  By CTB - December 22 - 12:46 am

  Outstanding sport car in a sedan body; great vehicle for those that like a blend of luxury, quality and speed

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  Wow! - 2006 Infiniti M45
  By Leejack - December 2 - 11:30 pm

  All I can say is wow! The the powerfull V8 is as smooth as butter and the transmission seems like it can read my mind. Performance like this along with all the bells and whistles you could ask for make this a great vehicle.

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  Best full sized car I have ever owned. - 2003 Infiniti M45
  By voltag19 - November 22 - 2:00 am

  This fine car has unlimited power to spare.

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  2003 Q45 Oil Consumption, Defec Brakes - 2003 Infiniti M45
  By 2003 Q45 - November 20 - 4:20 am

  I purchased the Q45 in March 2003 and have 16k miles on it now. It has always been service by Infiniti wihtin the manufacturer specs. When I picked up the car, the front rotors were warped...they cut them. This problem has persisted over the past three years and they simply cut the rotors. Secondly, the car burns over 1 quart of oil per 1000 miles. As everyone else has experienced, Infiniti denies there is a problem, states that burning 1 quart per 1000 miles is normal. If you persist, they will then go through the "consumption test" and will try everything they can EXCEPT FIX THE PROBLEM. It borders on criminal to sell someone a $60K car with these problems and not fix the car.

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  Terrific Performance Sedan - 2006 Infiniti M45
  By Linda - October 8 - 10:23 am

  I love this car! I have owned it for 2 years and have no complaints. I owned a Corvette before this car and wasnt sure how I would adjust to driving a sedan but this one has it all. It performs well, the power is there, the transmission is very smooth and it handles corners beautifully. The interior is very comfortable and visually appealing. It has a sexy exterior (I added the rear spoiler). The technology is easy to use (although the voice activation takes some getting used to). The stereo is amazing and having XM radio is great. I have the Dolby surround sound and it is like sitting in a concert hall! Having the Bluetooth is handy. Keyless ignition and entrance is a great touch.

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  Power, Raw Power - 2003 Infiniti M45
  By James M - September 15 - 2:00 am

  We had been looking for a new car and just happened on Infiniti, I took a Q- 45 for a ride first then a G-35 witch I realy liked but it was a little to small so the salesman says we just got a new car in want to give it a try, I said why not. Me and my wife took it for a ride and that was all it took after I hit the gas peddle the first time we looked at each other and knew this was it. This was Oct.2 ordered Oct 4 and took delivery Jan. 13 and have put almost 7,000 miles since.

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  What a car!!! - 2006 Infiniti M45
  By Preston Ingalls - August 10 - 9:20 pm

  I love this car. I traded my 2003 G35 in for it which I loved but this is such an upgrade. The comfort on the road, the awesome Bose sound system, the handling and the speed for passing leaves one breathless. After looking at Beamers and Lexus, why would you buy one of those when you can have this??? I can see why Car and Driver mag selected it as the best in its 8-car class for luxury cars.

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  The Beast Within - 2006 Infiniti M45
  By jrh332 - July 28 - 10:00 am

  Had my choices narrowed down to Audi A6 S line or the M45 Sport. Infiniti won hands down and didnt hurt being roughly $8000 cheaper with about the same equipment level. I know it doesnt have all the Audi features but the Audi doesnt have all the M45s equipment either. Truely a drivers car. The performance out of this 4000 lbs car is something you have to experience. Performance tires may pick up some noise depending on pavement otherwise as quiet as sitting in your living room. Controlled ride and appears to be screwed together pretty good.

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  It will be hard to beat the M45 Sport - 2006 Infiniti M45
  By Lonny53 - July 23 - 6:50 am

  This car is simply awesome. The power and road handling are outstanding. I have just finished the break-in period and I am starting to see how quick and agile this car is. I have the Tech and Journey packages and the technology in this car is incredible. Everything works well (once you figure out how to use it all). This is WAY better than any other car I have ever owned. The competition should be scrambling to catch up.