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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  Wicked Fast - 2003 Infiniti M45
  By BlackM45 - November 16 - 10:00 am

  Ive had my M45 for a week now. It is by far the fastest sedan I have driven. It will smoke a 540, E430/E500, GS430, A6 4.2 for $10K to $15K less. The look is menacing, especially in Black. The 18" wheels with the low profile tires look HUGE. The interior is first rate and very quiet.

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  Un diplomatic fun! - 2006 Infiniti M45
  By ? - November 12 - 4:56 pm

  I have driven an X5, XK8 coupe, Range Rover and a S Type in the past 2 years. I have been HAMPERED with problems with the RR and the XK8 and finally decided to try somthing more reliable upon a freinds recommendation to try the M series. I literally left 5 minutes before signing the for an Audi 6 and thought Id at the very least try this car. I did, I bought it and its really a tremendous car. Did I just jinx myself? Anyway, to date love it. The air conditioned seats! What a treat. Im 35 years old and its the perfect sporty sedan for me. Chris J. Meza

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  Quiet Power - 2003 Infiniti M45
  By Woodrow - November 4 - 2:00 am

  Its hard to stay out of the throttle in this car. Just turned 10,000 miles and so far have had only a couple of minor problems. To date I have not seen another on the road and the car definately gets alot of looks. It seems to run stronger if it is driven reasonably hard most of the time. Fuel mileage is not bad for a car of this weight and displacement. Averaging 18- 19 MPG.

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  Smooth, fast and love it - 2004 Infiniti M45
  By rocketgirl - September 30 - 9:26 pm

  Super powerful, handles smoothly, very comfortable. We call it the rocket for the super quick smooth acceleration. It is so great on the highway and around town. Has been very reliable.

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  fast and luxurious - 2006 Infiniti M45
  By amy agnoli - August 22 - 10:03 pm

  This car is an absolute pleasure to drive. The interior is very luxurious and the navigation system is very easy to use. I have had the 5 series BMW and I prefer this car for reliability, and interior comfort, (and the cup holders dont break!!!) Additionally, it has a very sporty, responsive feel that equals the bmw. I love it.

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  Sporty + Luxurious - 2003 Infiniti M45
  By ChristinaG - August 3 - 3:46 pm

  Purchased this car at 54K miles, still under warranty. I find this car to be a happy medium after owning a sporty BMW M3 and a luxury BMW 745i. It is quick like M3, excellent power and performance, but rides way more comfortably and has all the gadgets like the 745i. At 80K miles, I get an average 19.5mpg to the tank and have had only minimal upkeep. A tire pressure sensor needed replaced before 60K miles and the fuel gage, I found out after running out of gas on 1/2 tank, does not register accurately (a $200 part). Other than that I just love it. Roomy trunk, just enough back seat room, great stock stereo options. Rare model so it gets a lot of looks.

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  Best car in its class - 2003 Infiniti M45
  By HMSRelentless - July 30 - 10:00 am

  Ive owned BMW 7 series, Jaguar, etc. This vehicle(M-45) is by far the overall best of its class. I would rate it above the Jag. Lexus or BMW.

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  Fast & cheap - 2003 Infiniti M45
  By Ex-Lexus - June 29 - 2:00 am

  This car is the best buy in its class. The features would cost 10k more on BMW, Lexus and Mercedes.

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  Clark Kent turns into Superman - 2003 Infiniti M45
  By PrinceCharlie - June 12 - 2:00 am

  This car may look like Clark Kent (although I disagree), but touch the accelerator and Superman appears. I think this is one of the most striking vehicles (appearance-wise) on the road, and everyone who sees it agrees. (Hint: if you get the spoiler, chrome wheels and tint the windows, you turn a pretty good-looking car into the ultimate Pimpmobile. A dang fast Pimpmobile at that.) My car is graphite color (dark gray) with the graphite (black) interior. I get tears in my eyes every time I see it. Oh, did I mention its the fastest car Ive ever owned, and it has more horsepower than my last two cars (BMW 525 and Infiniti G20) combined? Sweet.

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  This car rocks - 2004 Infiniti M45
  By OTAKU - May 26 - 10:00 am

  This is my second Infiniti,, had an I30 first. This car maker blows the competion away in quality and design. I adore my car!