2006 Infiniti M45 Sport Road Test

The mid-size luxury car market is, quite frankly, overstuffed and bursting at the seams. There's a veritable alphabet of choices: Acura, Audi, BMW, Buick, Chrysler, Cadillac, Ford, Hyundai, Infiniti, Lexus, Mercedes-Benz, Pontiac - they all offer completely competent mid

The mid-size luxury car market is, quite frankly, overstuffed and bursting at the seams. There's a veritable alphabet of choices: Acura, Audi, BMW, Buick, Chrysler, Cadillac, Ford, Hyundai, Infiniti, Lexus, Mercedes-Benz, Pontiac - they all offer completely competent mid-sizers stuffed full of power, (varying amounts of) prestige, and poise.  This is because the mid-size luxo sedan sits in a sweet spot in the market: lots of volume, more prestige than entry-level luxury cars, but a more reachable price tag than top of the line cars.  There's almost more choice than there are buyers.

This is good news for the consumer, of course.  There are a lot of these cars fighting for a relatively limited number of consumer dollars, and they have to do everything right.  Performance, comfort, build, appearance, prestige - they all need to be there for these customers to sign on the dotted line.  And traditionally speaking, there have been two cars that have been the best at that - the BMW 5-series and the Mercedes-Benz E-Class.

2006 Infiniti M45 Sport

These two cars were basically yin and yang; the Merc's soft ride and staid styling to the BMW's crisp suspension and Teutonic minimalism.  Obviously, the market has expanded greatly since these car's respective heydays, and we are blessed with a glut of choice.  For those who like to do things differently, it's worth taking a look at the Infiniti M45 Sport.

The M45 is Infiniti's flagship model since the demise of the Q45 sedan in 2006.  It sits above the G37 sedan in Infiniti's lineup, and is a traditional front-engine rear-wheel-drive sedan.  This is technically the second generation M45, but the first one was a largely forgettable (and unattractive) market flop, so we'll skip that.

The M45 (and it's V6-powered brother, the M35) are Americanized versions of the Japanese-market Nissan Fuga sedan.  In Japan, the Fuga is available in 250GT, 350GT, and 450GT forms - 2.5L and 3.5L VQ V6's and the 4.5L VK V8.  Here, only the large V6 and the V8 are available.


Let's talk about that engine, because it's really the star of the car.  The VK45DE is the evolution of the older VH45, which debuted with the original Q45 back in 1989.  It's a 4.5L all-aluminum design, utilizing dual overhead camshafts per cylinder bank and 4 valves per cylinder.  Power output is a turbine-smooth 335bhp@6400rpm and 340lb-ft (460nM).  It's only available with a driver-adaptive 5-speed automatic transmission.  With a kerb weight of 3995lbs, this gives a pretty healthy power/weight ratio of 185bhp/ton.

The chassis is a stretched version of Nissan's acclaimed "FM" (for Front-Midship) platform, which also sees duty in the Infiniti G sedan as well as the Nissan 350Z.  The engine sits mostly aft of the front axle, which gives a surprisingly neutral weight distribution of 54.1/45.9 front to rear.  The M45 sport is rear-drive only, but an all-wheel-drive M45x is available with Nissan's excellent ATTESSA-ETS 4WD system.

The greasy bits only tell part of the story, though.  The Infiniti M45 has a heavy bias towards technology, and the list is immense.  For one thing, how about a 14-speaker Bose stereo with Dolby 5.1 surround sound with speakers built into the seats? Then there's the laser-guided cruise control, lane departure warning system (massively annoying and thankfully defeatable), DVD-based Satellite Navigation, Bluetooth hands-free connectivity, a full-color backup camera that pops up in reverse with steering-dependent guidelines, satellite radio, adaptive cornering bi-xenon headlights, 6-disc CD changer...  Oh, then there's the heated and cooled seats, the voice-activated controls for everything, the keyless entry and keyless start, the rain-sensing wipers and automatic headlights... you get the point.

2006 Infiniti M45 Sport interior

It's a bit overwhelming, to be honest.  Infiniti uses a BMW-like control knob mounted on the center console which is awkward to use and unpleasant to look at.  It works, but I'd rather have buttons - what's so difficult about buttons?  Then the lawyers get in on the game, forcing you to be stopped and in park to input a location in the satnav, which is just obnoxious - that's what passengers are for.  Oh, and the lane departure warning - NO.  Why would I want something that beeps loudly at me every time i change lanes without using my turn signal?  Why in the world?  No.  Delete.  Destroy.  Also, why is there no auxiliary input or iPod adapter?

ANYWAY, most of this technology is great.  It makes life easier and makes commuting more pleasant.  The stereo is absolutely mind-blowing; perfect for hearing every note in Stairway To Heaven at ear-bleeding volume, or being a hippy and listening to NPR.  It's up to you.  On road trips, the XM satellite radio is a blessing.

The seats are heavenly - perfectly padded and nicely supportive, and the cooling feature is something you wonder why you've never had before on a hot summer day.  Long story short, it's a relaxing, extremely comfortable car to drive - just as you'd expect it to be.


Of course, this is CarThrottle, not Nerdy Electronics Weekly.  We are more into torque and tire smoke than satnav and butt massagers.  So how does the car drive?

Depress the brake and punch the "Start/Stop" button and the V8 cranks over all by itself.  The gauges do a full-sweep and light up, and you're ready to go.  Throttle take-up is surprisingly smooth for a car with an automatic - not such a slushy automatic.  The VK45 sounds marvelous, smooth as silk with just enough bark to let you know what's under the hood.

It's quite docile around town at low speeds, but put your foot in it and the M45 responds right now.  This is the kind of power only a well-designed twin-cam V8 can make; power anywhere.  Power only starts to fall off well north of 6,000 rpm.  While the M45 is shy a few horsepower on the competition (E550: 382, Genesis V8: 375, 550i: 360, etc.) it never feels anything close to underpowered.  The transmission is relatively intelligent for a traditional 5-speed automatic, although the lack of shifter paddles on the steering wheel is a confusing oversight on Infiniti's part.  The M45 sport comes with stiffer suspension than the regular M, as well as 19" alloys with summer performance tires (245/40/ZR19 Bridgestone Potenza RE050A's) which stick like glue.  Most interesting is the use of Nissan's proprietary HICAS 4-wheel-steer system, which only comes on the sport model.  It's not nearly as drastic as you'd think, but it gives this big, heavy sedan the kind of turn-in and responses you'd expect from something smaller and lighter.  The brakes have no problem dealing with the weight and inertia, and display no signs of fade even in hard driving.


I had the chance to get impressions of the M45 over a nearly 5000-mile road trip, from Raleigh NC out to Warm River Idaho, and back via most of the country’s main East-West interstates. This car is a champ on the highway. While the Sport model certainly rides rougher than the standard M45 Luxury model, thanks to 19" low-profile tires and stiffer suspension, the trade-off is worth it: the M45 Sport has that locked-in-guided-cruise-missile feeling on the highway that only powerful, heavy, well-designed cars can enjoy. The innate stability of this car on the highway is a blessing and a curse. It’s great in the mountains, but when driving across I-80 in Montana and South Dakota, the driver quickly becomes irritated that the cruise control won’t maintain speeds above 90mph. It’s that stable.

We got to drive the Infiniti over a large variety of roads, including the infamous Tail of The Dragon (or Deal’s Gap), which is an 11-mile stretch of US-129 between North Carolina and Tennessee that has 318 turns. Over this extremely challenging piece of road, the Infiniti’s sports-car based heritage comes through loud and clear. Despite the relatively heavy kerb weight and long wheelbase (well, for a road like this), the M45 has absolute poise and balance, and the V8 with the shiftable automatic provide tons of low-end torque for ripping out of low-speed corners. We were able to easily keep pace with a manual-transmission BMW 335i Coupe, which is a car that is arguable much better suited for such a road. The Infiniti’s artificially heavy steering really comes to life on challenging roads like this, with just enough feel to know what the front wheels are doing.


Handling is, unsurprisingly, very neutral. The predominant characteristic is mild understeer, although with 245/45/ZR19 tires, it is quite hard to provoke. One downside on roads like these is that the stability control system is far too aggressive, cutting power in situations where it’s simply not needed, or at least to the degree that the system intervenes. Even with the program disabled, it still intervenes in some situations. While it’s better to be safe than sorry, a car designed for enthusiastic drivers like this one really should have a totally defeatable stability control system. The large four-wheel disc brakes exhibited no fade even after repeated runs down The Dragon, the temperature gauge never twitched, and it generally kicked ass and took names - so to speak. The only negative aspect shown on the Dragon was a result of the highest octane locally available being 89. With the high altitude and large engine loads placed, the VK’s knock sensor was working overtime on some tight corners. This is certainly not a fault of the car, but just an observation. For more information on The Dragon, check out this post.

Overall, the M45 is a compelling choice in the mid-luxury market.  It's attractive, well built, immaculately engineered, and remarkably devoid of annoying flaws - over technification aside.  The pricing is quite attractive for the market it's in, as well.  It's definetely worth a look.

Test Car: 2006 Infiniti M45 Sport

Options: Technology Package, Sport Package Base Price: $50,250Price as Tested: $56,695

Layout: 4-door sedan Drivetrain: Front Longitudinal Engine, Rear wheel drive Engine: VK45DE 4.5L DOHC 32v V8 Transmission: 5 speed shiftable automaticPower: 335bhp @ 6400rpm Torque: 340lb-ft@4000rpm

Weight (Kerb): 3995 lbs Bhp/ton: 184.8

Performance: 0-60mph, standing start: 6.2 seconds (average) Top speed: 155 *mphFuel mileage: 16 city/21 highway (Revised EPA Testing Method) *Electronically limited, claimed

Highs: Smooth, Powerful V8. Nice weighty steering. Surprising balance and overall performance for size. Great shape, good value, well-built. Lots of gizmos.

Lows: Bump Steer, Orange Gauges, No iPod adaptor is a huge oversight, Lane Departure Warning is annoying, 22mpg highway.

Conclusion: A good performer and a good value, relatively speaking.


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