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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  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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  2006 M45 Sport - 2006 Infiniti M45
  By Brettrun - March 12 - 9:33 am

  I have had this car for about two weeks now and it has been awesome! It replaces a G35 coupe and the difference in fit, finish and quality is amazing. I had two G35s and always was disappointed by the cheap and often squeaky interior. The M45 is a world apart in terms of materials and and the feel of quality. If anything, the car is faster too. There is no substitute for pure V8 power and torque! The list of technology and features on the car is a huge leap also. Especially if you love the gadgets like I do. I compared the Lexus GS and Acura RL and found the M45 to be the best choice for me. It is more of a SPORTS luxury car, but has all the features of the other two if not more.

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  Its going to be a classic - 2004 Infiniti M45
  By Karl - February 3 - 8:13 pm

  Bought my 2004 brand new right after my BMW 540i came out of the shop, Again. It is an awesome car that is not well known. I took a BMW 530 to task with no problem. No one knows what this "sleeper" can do. Most dont even know what the M45 is. At 70 MPH this car is asking you to please let it go faster. At 100 MPH its asking to please open it up all the way. During that time it feels and handles like a German car and the stereo is going, so pay attention to your driving. If you cant handle or appreciate very fast cars, go get a something else. This one is a dark horse among many wannabes. At todays prices its a steal. They wont be so low for long.

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  fantastic car - 2006 Infiniti M45
  By JEFF - December 21 - 9:40 am

  This car is really fun to drive; terrific acceleration on the freeway. As a former Lexus owner, the road feel of the M45 is a welcome change from riding in a cocoon. The dash console is attractive but a little confusing. Sirius satellite radio is a big plus.

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  Best Performance and comfort - 2004 Infiniti M45
  By Sam - November 26 - 11:00 am

  Best Sedan performance plus quality for the money in America, specially 1-2 yr old used one. Smooth and quiet at high speeds. Great stereo.

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  Still drives very well - 2003 Infiniti M45
  By qualityfirst1 - September 5 - 6:00 pm

  This car had lots of positives, but the few negatives does sour our ownership experience. Our M45 has a very unique look, which Ive come to like. The interior is still very nice. Our car still drives very well - it doesnt feel like 108K mi. The power is very impressive. The aluminum suspension components cut unsprung weight. A lot of things have broken, which is upsetting. Infiniti service writers are nice, but they will not fight for the customer. Our air bag light has been on since a hair over 50K mi. The warranty is good up to 7yr/70K, but they wouldnt fix it. The oil issue stinks. Due to the bad service, I wont buy again.

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  Problem with headlights - 2007 Infiniti M45
  By pep - June 25 - 3:00 pm

  Everything that you have read about this car is true (its great), its hard to believe anyone being disappointed with the M45 Sport. However if you drive this car on the highway at night, you need to know that the design of the headlights is faulty. The high beams are focused so high that they do not illuminate the road in front of the car at all. There is a single adjust for both high and low beam lights so if you take your car to the dealer they will misalign the low beam focus if you complain of the faulty high beams. I drive 70 miles at night on a desert highway to work daily, if you drive your M45 in town this will not be an issue.

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  Charlotte NC - 2006 Infiniti M45
  By JP - January 26 - 3:36 pm

  Fun car to drive, AC seats are awesome, my wife says everyone stares at the car when she takes it out but its really her. I have the sport package and it is great, I also have a 1 yr old and do not suggest the car as a alternative to the minivan

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  Refinement Needed - 2003 Infiniti M45
  By Roadglide99 - December 2 - 2:00 am

  Well the ergonomics could be better. The shifter, cup holder and armrest need to be reconfigured. So does the CD player (single in-dash is preferred). I have 3,500 miles on the car and I had a problem with the Trans. getting stuck in 2nd. gear @1,200 miles. Tried everything, finally shut the engine off and restarted, appears ok. The dealer tested it repeatitally with nothing found (the trans. is lazy while in automatic mode, when stepping on the gas to down-shift and pass). Oh the gas milage does stink, and I dont drive it wildly, ok very seldom... getting about 18mpg.

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  Save money, buy lexus - 2006 Infiniti M45
  By CHUCK - October 6 - 11:50 am

  A little harsh ride and quite noisy for a $50k plus vehicle. This clunker has been in the shop almost as many days as its been on the road. "Smart" cruise control shuts off if headed into the sun. Lane departure system beeps when Im in the middle of the lane. Brake cylinder needed to be repaired, door seal deteriorated, AND I ONLY HAVE 7,000 MILES ON IT!!! Looks great but Lexus makes a much better vehicle in the ES330 and GS series and the Lexus ownership experience is far superior (I also have a Lexus SC 430). Dealership treats me like I bought a Yugo. I have already traded this piece of crap after only 6 months on an ES 330.