2009 Infiniti M45x Review

By Chris Haak



Six months ago, I reviewed the Infiniti M45’s cheaper, less powerful cousin, the M35S (S for “sport,”) and declared that there was no need for the additional horsepower that the more expensive M45 offered via its 4.5 liter V8.  And while that original conclusion is still true – who actually needs to go from 303 horsepower to 325 horsepower after all? – the M45 sure does have a sweet V8 engine under its sculptured hood.  It’s anything but reasonable for me to claim that a 325-horsepower 4.5 liter V8 is lacking in power or torque, but it’s not a problem that the likely installation of the larger 400-horsepower V8 in the upcoming third-generation M56 couldn’t cure.

The “old” 4.5 liter V8, though, is still an engine that has plenty of pep.  While it may not top the 303 horsepower 3.5 liter V6 of the M35 by much on paper, it does provide a bit more kick in the pants, and more importantly, offers a lot more smoothness and refinement than the still-very-good VQ V6 does.  Since the M45 is (at least relative to the M35) nearly all about the engine, I’ll also mention that the M45’s V8 has a nice snarl under acceleration that’s several decibels quieter than the M35’s V6 and far less noticeable than the growl of V8s in more performance-oriented cars like the Dodge Challenger SRT8 or a Pontiac G8 GT.

08_m45x04As I look back on my week with the M45x, which was provided by Infiniti, it’s hard to recall a vehicle that was a more comfortable, capable highway cruiser.  I found it surprisingly easy to fit my entire family of four (which includes two large convertible car seats) into the car, luggage for an overnight trip that included a double stroller, two soft duffel bags, and even a large part of a hose reel that my father had repaired for me.  My sons didn’t kick the seatbacks behind them, and in spite of having to make a slight seat adjustment compromise to give them a little more room in the back seat, there wasn’t as much give-and-take as is typical when putting my sons behind my 6’4″ frame in a regular car.

The car’s cabin is well-isolated from road, wind, and (sometimes unfortunately) mechanical noises.  Regardless of my speed, with the windows up and the sunroof closed, it was all but impossible to detect just how fast I was driving.  This is something of a bad thing for drivers who don’t tend to pay close attention to their speedometer, but a good thing when the driver’s wife is in the front passenger seat reading a novel, oblivious to the rate at which scenery was streaking past her window.  The front seats were comfortable on numerous two-hour stretches of highway, though lacked some of the support that I found in the M35S’ sport seats.  The leather on those seats is soft and of high quality, as is appropriate for a nearly-$63,000 car.

08_m45s14So-called “infotainment” options are prolific in the M45x.  While the car did not have a flip-down rear seat DVD player, it does have a large DVD video/audio player unit taking up a third of the center console.  With the car in park, the DVD movie can be displayed on the large navigation screen in the middle of the dashboard, but of course, the movie becomes audio-only when the car is in motion.  Aside from the DVD input source, other options were AM, FM, XM, CD changer, iPod, music box (internal hard drive), auxiliary, and compact flash.  I’ve never seen a car with so many input sources.  The auxiliary feature is capable of accepting a standard three-piece RCA-style plug from a portable video game system or DVD player, so to entertain my children, we plopped our Sony DVD player onto the center console lid, plugged its 12-volt power adapter into the power point at the back of the center console, and plugged the DVD player’s line-out cable into the three inputs.  With this setup, the kids were able to watch the movie on the portable player’s display, while the sound was piped throughout the car’s sound system.  As with the factory-installed DVD player, the auxiliary video input also can display on the navigation LCD screen when the car is not in motion.  I still haven’t figured out much of a purpose behind installing a DVD player that only works when cars are at rest.  The best that I can think of is when I put a how-to-detail-your-car DVD into the dash-mounted DVD player in my Cadillac CTS, but that’s a pretty limited example.  Of note is the fact that rear wheel drive Ms are available with a motorized fold-down DVD screen, but it’s apparently not even available in the all wheel drive models.

08_m45x11As with the M35s that I tested six months ago, the M45x was equipped with Infiniti’s excellent million-speaker (actually 14), million-watt (actually 308) sound system that put two small speakers at the top of each front seatback.  It’s not the best audio system that I’ve ever listened to, but probably the best Bose system I’ve ever heard.  Clarity and power are both very good.  While I’m not an expert on car audio systems, the best I can hope for is that both low volumes and high volumes are clear and distortion-free.

As mentioned earlier, acceleration was brisk, but not breathtaking.  Three hundred twenty five horsepower from a medium-displacement V8 just isn’t an impressive stat anymore.  The M45x’s added heft – from both the larger engine and from the all wheel drive hardware – coupled with two fewer gear ratios than the rear wheel drive M35s that I tested earlier – made the car, from the perspective of the seat of my pants, feel no faster than the less-expensive M35s.  In fact, Infiniti provides a curb weight of 4,135 pounds for the M45x and 3,865 pounds for the rear wheel drive M35.  In terms of power to weight ratio, each horsepower has to move 12.72 pounds of M45x, but each one only has to move 12.75 pounds of M35s.  No wonder the car doesn’t feel any faster.  The gear ratio advantage that the M35 has (a lower first gear and a higher top gear), the lack of AWD driveline drag, makes the M35s the quicker car in a straight line, and the M35s, with its sport suspension, 19 inch wheel/summer tire combination, and rear-wheel steering make the contest on curvy roads unfair in favor of the cheaper car.

08_m45x05Because the M45x doesn’t have the sport suspension and larger/stickier wheel combination found in the M35 with the Sport Package, it didn’t handle as confidently.  The big car still had some decent moves, but the suspension tuning was focused more on ride comfort than on handling capabilities – not a choice I’d personally be making.  After a particularly hard run, with aggressive acceleration and braking, the M45’s brakes were quite hot, though I did not notice any fade.  The Sport Package in the M35 does not seem to include upgraded brakes, so that is either an indication that the standard brakes are pretty good, or that the Sport Package is cutting corners by not upgrading the brakes.  My guess is that they’re good brakes, period, and that the difference in my perceived stopping abilities between the two cars is attributable to the M35’s larger tires with sticky summer compound.  (The M45 had all-season tires).

Cars like the M45x aren’t about at-the-limits handling and braking, anyway.  They are about coddling their driver and three passengers (yes, there’s a rear-center seating position, but who wants to sit there in a car with a large driveshaft tunnel?) in comfort and luxury.  They’re about getting to one’s destination relaxed and refreshed, and about effortlessly gobbling highway miles. The M45x did all of those things with aplomb.  Sadly, the car also gobbled premium unleaded, with observed fuel economy just over 15 miles per gallon (the EPA rates the car at 14 city/20 highway, and that’s poor enough to earn the M45x a $1,300 gas guzzler tax).  In contrast, the M35s that I keep referring to is rated at 17 city/25 highway, thanks to its smaller displacement, fewer cylinders, and a lighter weight car to lug around.

The pricing was somewhat steep, but there is a ton of technology and comfort features in the M45x.  Base price is $55,465 including destination, and my test vehicle had the $2,800 Advanced Technology package (Bose 5.1 Surround Sound system, Lane Departure Warning, Lane Departure Prevention, Intelligent Cruise Control), and the $3,350 Technology Package (hard drive navigation system, XM NavTraffic, 9.3 GB music hard drive, iPod connectivity, voice recognition, and a rear view monitor).  All told, the final MSRP came in at $62,915.  While Lexus doesn’t make an all wheel drive V8 GS, the rear wheel drive GS460 is actually cheaper according to TrueDelta, but the M45 undercuts the BMW 550i by about $10,000 (rear wheel drive versions of both cars, since the BMW isn’t available with the AWD/V8 combination either).

If you like the shape of the current-generation Infiniti M, you may be able to cut a good deal in the coming months, as the all-new 2011 Infiniti M37/M56 were revealed in the past day and a half.  The new cars have far more engaging, modern styling, more power, and many new features.  Of course, they’re probably going to cost a lot more, too.

Should you have the budgetary flexibility to buy a large, powerful sedan that can hit triple digit speeds without batting an eye – or letting its passengers know that it’s doing so – and you can afford to operate a car that gets 15 miles per gallon, the Infiniti M45x should merit strong consideration.  Personally, I’d skip the all wheel drive unless you lived in the snow belt and skip the V8 to save lots of money at the time of purchase and at the gas pump.  I tip my hat, however, to a great road trip car.

COPYRIGHT Autosavant – All Rights Reserved

Author: Chris Haak

Chris is Autosavant's Managing Editor. He has a lifelong love of everything automotive, having grown up as the son of a car dealer. A married father of two sons, Chris is also in the process of indoctrinating them into the world of cars and trucks.

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  1. I hope the new one is better-looking because this one is no great shakes in the looks department.

    This car is a pleasure to drive despite it’s average looks. It’s not a sports car, but it is a great luxury cruiser.

  2. I like the way it looks. I think it looks refined. Japanese, but refined.

  3. i like it too. Looks good.

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