2008 Infiniti M45X review: 2008 Infiniti M45X

Pricing Unavailable
  • Trim levels M45X
  • Available Engine Gas
  • Body style Sedan

Roadshow Editors' Rating

8.1 Overall
  • Design 10
  • Features 6
  • Performance 8

The Good Cabin technology in the 2008 Infiniti M45x includes a hard-drive-based navigation system with traffic reporting, a great-sounding stereo with many digital music options, adaptive cruise control, and an innovative lane departure system.

The Bad The engine doesn't strike a great balance between economy and power, excelling at neither, and the five-speed automatic transmission didn't feel particularly modern.

The Bottom Line The 2008 Infiniti M45x offers some of the most cutting-edge cabin tech at a rock-bottom price, compared with the competition. The car is a good luxury cruiser with some performance aspirations.


Photo gallery:
2008 Infiniti M45x

When you think big, comfortable sedans with cutting-edge tech, you look for a price range around $80,000 to $100,000 and think models such as the Mercedes-Benz S-Class, BMW 7-series, and Lexus LS. But then here comes the 2008 Infiniti M45x with all the tech those other cars offer for a measly $60,000, fully loaded. This is the car for well-heeled value shoppers.

The M45x model is Infiniti's top-of-the-line sedan, featuring the model's largest motor along with all-wheel drive. This big sedan cruises easily and coddled us in its very comfortable front seats. Infiniti has been a real leader in cabin technology lately, and our M45x test car came with not only the optional Technology package, but also the Advanced Technology package. There are only a couple of places where we felt this car let us down, in its uninspiring automatic transmission and its mediocre fuel economy, which was expected given the size of the engine.

Test the tech: Traffic cruise
The 2008 Infiniti M45x includes a couple of cutting-edge technologies as options: XM NavTraffic and adaptive cruise control. We tested both of these with a rush-hour trip into heavy traffic around San Francisco, a city consistently rated in the top five for worst traffic in the country. We've used adaptive cruise control, a radar-based system that slows the car down to the speed of slower-moving traffic ahead, on freeways with sparse traffic. Even there we kept a foot hovering over the brake pedal, at least initially, afraid to put our trust into the system. But we were ready to take the next step and drive in heavy traffic, sans feet.

The adaptive cruise control is set for 72 mph, according to the display on the tachometer, but slower traffic ahead has the car's actual speed at just below 60 mph

And we also used the opportunity to test the traffic avoidance feature of the navigation system. With the Infiniti, as in a few other cars we've seen, such as the Cadillac CTS, the navigation system uses the information it gets about traffic on the road ahead to come up with alternative routes. This level of integration beats the systems that merely show traffic information without warning about traffic jams on the road ahead.

We set our initial route for the San Francisco International Airport, a few miles south of the city, and followed the route onto the freeway. Traffic was stopped in the other direction, but we got enough clear space southbound to gun the car up to 70 mph and set the cruise control. As we came up on the traffic ahead, our hearts pounding, the car braked and slowed itself to 45 mph, matching the speed of the car in front of us. The distance between our car and the next was initially pretty far, and would tempt too many people to cut in, so we pushed a button on the steering wheel that brought the following distance to the lowest setting.

In a few stretches just south of the city, the navigation screen showed an amber line along the freeway, indicating traffic moving at 20 mph to 40 mph, but the navigation system didn't suggest an alternative. We figured it would only suggest a different route for traffic going below 20 mph, indicated on the map by a red line.

This dense traffic is moving slower than the 20 mph to 40 mph indicated on the navigation screen.

As we drove under the cruise control's speed management, we felt that the car we were tracking was going a bit too slow, about 5 mph under the limit, so we looked for a clear spot and jumped a lane to the left. Our car immediately sped up, trying to reach the 70 mph it was set for, but quickly locked onto the car ahead, and we settled in at a more comfortable pace. But following this car, a minivan cut into the space between us. There wasn't a lot of room, and the M45x started slowing down. But we just didn't feel it was enough, so we hit the brakes harder to avoid a collision. We concluded that the adaptive cruise control does work in even heavy traffic, as long as it's moving along, but you have to be ready to get a foot on the brake when needed.

For the trip back, we set our destination as CNET headquarters, and the navigation system advised us that it adjusted our route based on traffic ahead. We looked at the entire route and saw that it wanted us to exit the freeway before a red section in downtown San Francisco. So far, so good. We got on the route, but quickly got into very slow moving traffic running well under 20 mph. Looking at the map, it claimed we were only in an amber section, and should be moving faster. This is a problem with the reporting and not Infiniti's system. If the traffic conditions were up-to-date, the navigation system would have routed us off the road. As it was, we took the next exit off and devised our own detour.

In the cabin
Our 2008 Infiniti M45x featured most of the same cabin tech we saw in the Infiniti EX35, and it is all very good. An LCD sits in the center of the dashboard with a set of controls on a panel below it. The main controller is a big, multifunction knob with directional buttons inset on top of it. We like this setup a bit better than the joystick/knobs found in BMW's iDrive and Mercedes-Benz's COMAND interfaces. Infiniti also supplements the buttons and knob with a touch-screen LCD, but in the M45x, the screen is too far from the driver for that aspect to be useful. There is also a voice-command system that replicates most of the controller commands.

The multifunction knob on the control panel is supplemented by the touch screen.

The navigation system included in the M45x's Technology package stores its map data on a hard drive. That and its quick processor make for fast route calculation and map rendering. The hard drive also allows for some very detailed information storage, such as outlines of some buildings in major urban areas and 3D map views. For destination entry, the multifunction knob makes it easy to select letters and numbers from the onscreen keyboard. The system also offers a complete points-of-interest database.

We were also happy with the route guidance, which uses detailed graphics to show upcoming turns and text-to-speech, reading out the names of streets. We mentioned the live traffic reporting above. Along with traffic flow information, the system shows incidents, such as road construction or accidents. There are too major traffic systems in cars right now, XM NavTraffic and Clear Channel's Total Traffic Network. In the San Francisco Bay area, we've noticed slightly better coverage from the Clear Channel service, but NavTraffic seems to be catching up. It showed traffic information on a highway through the center of the city, something we hadn't seen previously from this service, although it didn't have a highway south of the city that is covered by Clear Channel.

For entertainment, the M45x offers an almost ridiculous number of audio sources. Along with terrestrial radio, it has XM satellite radio. There is a single CD slot on the center stack, which can play MP3 CDs, and a DVD player in the console. You can play MP3 files off of a compact flash card inserted in a slot on the center stack or listen to an iPod plugged into a port in the center console. The iPod interface is excellent, letting you select music by artist, album, and genre. With the DVD player, you can even watch movies on the LCD, although we're not sure why anyone would do that.

These shoulder speakers come with the Advanced Technology package, part of an upgraded Bose audio system.

And the audio system produces excellent sound. With the Technology package, you only get eight Bose speakers, but the Advanced Technology package upgrades the audio system to 14 speakers, complete with subwoofer, center fill, and four shoulder speakers mounted in the front seats. 308 watts of amplification power these speakers, and the audio is refined using Bose's digital 5.1 surround sound. This system results in very clear instrument reproduction throughout the spectrum. The bass isn't overwhelming, but it is nice and clear, while highs are very distinct. With the audio system and the comfortable seats, we just wanted to drive around all day.

On the communication front, Infiniti's Bluetooth phone system is generally good, although it requires you to push your phonebook into the car. Some systems, notably from BMW, upload your cell phone's entire phonebook automatically. Our phone only let us push one entry at a time into the Infiniti's system, but other phones will let you push the entire phone book. For manual dialing, there is a good onscreen keypad, or you can use the voice command system.

The Lane Departure Prevention feature is activated with a button on the lower right of the steering wheel.

Many cars stop at these three basics: navigation, digital audio, and Bluetooth, but the M45x keeps a few more tricks in the cabin. We mentioned the adaptive cruise control above. Other driving technologies include Lane Departure Warning, which sounds a tone if you cross a lane line without signaling, and Lane Departure Prevention, a new technology from Infiniti we first saw in the EX35. When you enable this system by pushing a button on the steering wheel, it slightly brakes the offside wheels if you continue to drift over a lane line after the Lane Departure Warning has sounded. This braking results in the car being nudged back into its lane. The system only works above 45 mph and it is easy to override, either by turning the wheel or using a turn signal. In practice, we found this system worked very well when we let the car drift over a lane line.

The last significant piece of cabin tech is the rear-view camera. Previously, we've been so impressed by the rear-view cameras in Audis that we've tested them with backward slaloms and other maneuvering. The reverse camera in the M45x uses the same technology, presenting an overlay that shows the car's proximity to objects behind it, and another that curves when the wheels are turned, showing the path the car will take.

Under the hood
The 2008 Infiniti M45x is the first time the M45 has been fitted with Infiniti's all-wheel-drive system. This system, also used in the FX models, can move torque from 100 percent rear-wheel-drive to a 50-50 split between the front and rear wheels. Infiniti claims the system not only helps during inclement weather--there is a snow setting to lessen torque as well--but also gives the car better sport handling.

The snow button reduces torque, making it less likely the tires will spin on slippery surfaces

We had very dry conditions during our review period, but did drive some winding mountain roads, putting on the power through the curves. During hard maneuvering, the car leaned a bit and the rear tires felt like they skittered over the pavement, but the car never really slipped. It felt like it had grip to spare, but because of the car's heavy feel, we never really could tell when torque was splitting to the front wheels.

The five-speed automatic transmission didn't seem to add much to the driving experience. It had the usual manual shift mode requiring a push up on the shifter to upshift, and down for a downshift. But gear shifts felt slushy--typical automatic behavior--not like some of more highly tuned automatics found in cars such as the Cadillac CTS or the new Mercedes-Benz AMGs.

The five-speed automatic felt like a typical automatic transmission, with no real sport turning.

With 325 horsepower and 336 pound-feet of torque, the 4.5-liter V-8 under the hood isn't the most powerful engine around. Instead, it seems as if Infiniti is trying to strike a balance between power and economy. The engine does give the car decent acceleration, but it's not overwhelming. It seems more that Infiniti realized people buying a big luxury sedan weren't going to push it hard through the twisties, so it tuned the engine for comfortable freeway cruising, making sure there would be power when you needed it.

The engine uses continuous valve timing technology to maximize efficiency, but even so, the car is subject to a hefty gas-guzzler tax. The EPA gives it 14 mpg city and 20 mpg highway. We averaged a bit more than 16 mpg, right in the middle of that range, not great, but about what we would expect from an engine this size. We've seen comparable fuel economy in six-cylinder cars. For emissions, the M45x gets California's minimal LEV II rating.

In sum
At a base price of $52,750, the 2008 Infiniti M45x comes in fairly cheap compared with a lot of the competition. Our car also came with the $3,350 Technology package and the $2,800 Advanced Technology package. Along with the $1,300 gas guzzler tax and the $765 destination charge, the total comes up to $60,965, still a good deal for a car with this kind of tech.

For our rating, we give the M45x top marks for its cabin tech. With the core technologies we look at, the M45x offers many advanced features. It adds a number of other technologies on top of that, including Lane Departure Prevention, something no other manufacturer has currently. In the performance tech category, we are less impressed. Fuel economy is far from wonderful, and it doesn't offer a particularly sporty drive as compensation.