2008 Infiniti M45X review: 2008 Infiniti M45X

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CNET Editors' Rating

4 stars Excellent
  • Overall: 8.1
  • Design: 10.0
  • Features: 6.0
  • Performance: 8.0
Review Date:
Updated on:

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.

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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.

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Where to Buy

2008 Infiniti M45X

Part Number: 100959726
Pricing is currently unavailable.

Quick Specifications See All

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