2008 Infiniti M45X review:

2008 Infiniti M45X

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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.

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