Is the BMW X5 an SUV or a mobile computing platform? BMW uses a 10-Mbps bus called FlexRay to keep this mid-size SUV stable at speed, employs a transflective LCD to improve readability in sunlight, and added six programmable function keys to the dash, in hope of making iDrive easier to master. The result is the new benchmark for luxury/sports SUVs that's attainable by the lucky few who can afford it. Most buyers won't drive out paying less than $55,000, and if so, they're still leaving $25K of options on the showroom floor.

BMW is the first automaker from an industry consortium to begin the switch from the slower CAN (controller area network) bus. The FlexRay bus controls the optional suspension that limits body roll in turns and electronically damps bumps. (Oddly, to get this feature, you must order the sports package.)

The transflective display on every X5 can be lit by sunlight as well as internal backlighting and that means you don't really need a visor overtop. The six new keys on the dash let you create a Take Me Home button or autodial your spouse's cell phone, but otherwise the iDrive cockpit controller remains daunting. The optional technology package has parking sonar, a backup camera, and green-yellow-red distance band in the display that dynamically highlights and displays the nearest objects as you back up. Bluetooth is essentially standard (meaning it's in the base options package that 95 percent of X5s have.

It's a BMW, so it has iDrive, the much-maligned cockpit controller. This version is improved in three small ways: It has a rubberized gripping surface rather than slippery metal, more climate control buttons are returned to the dash, and six presets at the base of the center console can be used like radio buttons but also for pre-set navigation destinations (home) or frequently used phone numbers. Otherwise, iDrive in the X5 remains the same: There's an incredibly long learning curve for entertainment, communications, navigation, and climate control features, followed several months later by relatively easy day-to-day operation. And it still zooms (enlarges) map displays with a counterclockwise motion, which is the opposite of what most people intuitively try.

There's an LCD in every X5. It's 8.8 inches diagonally if you order navigation, and 6.5 inches otherwise. And it's transflective, meaning it uses sunlight as well as backlighting for illumination. BMW employs a wide-aspect-ratio LCD, and on navigation models it's typically split two-thirds and one-third. That way you can have two info displays side by side, such as navigation and the trip computer. You can't, however, have the navigation map in the big window and audio information in the small window; only the other way around.

The X5's technology package combines the navigation system with front and rear parking sonar, a backup camera, and—this is really useful—green, yellow, and red warning bands that wrap around the closest objects in back of you, in the display. When the parking sonar senses an object, it places a green band in the display around the object; as you drive closer, the band turns to yellow. And when you're about a foot away, it turns red. If you back into something using this technology, you really weren't paying attention. A nit: The camera covers 120 degrees horizontally, but some cameras do 180 degrees.

Once you're underway, the Siemens VDO DVD-based navigation system is as good as any on the market. And with the split screen, you can have both a birds-eye-view moving map and directional arrows. But entering an address can be difficult because of the complexities of iDrive, a tricky voice-input system from Nuance, and unfathomable onscreen shortcut icons that take several iDrive slides, turns, and presses to invoke. The six preset buttons help a little.

You also get real-time traffic information via a partnership with Clear Channel Communications and Microsoft spinoff Inrixthat should be impressive in a year or so. Now it's little better or worse than other services. The real-time traffic data is free, but only because BMW hiked the price of the standalone navigation system by $100, to $1,900.

BMW offers a head-up display that is a worthwhile option, at $1,000. It projects only crucial information: your speed, warnings, and the next navigation instruction. The active cruise control option on most other BMWs isn't available, at least for 2007.

BMW's roundel (propeller) emblem on the hood is a reminder that the company started out as a builder of airplane engines. To this day, BMW's most technical elves spend their time buried under the hood. The six-cylinder engine develops 260 hp, and in combination with a new six-speed automatic transmission, launches the X5 to 60 mph in 7.8 seconds; the 350-hp V8 takes just 6.4 seconds. Given the cost, extra weight, $8,600 price premium, and 10 percent economy penalty of the V8 X5 4.8i, I believe most users will want the six. If you care about performance or comfort, you'll want the sport package (which ironically also provides the smoothest ride when you refrain from pushing the Sport button next to the shift lever).

The sport package gives you the adaptive ride system controlled by the new FlexRay bus. FlexRay is on tryout in the X5, and I expect it will show up controlling more than a dozen features in the next-generation 7 Series in 2008. Adaptive Ride comprises electronically controlled damping (shock absorbers) and the anti-roll stabilization (ARS) system. Just as airplanes bank into a turn, ARS, to a lesser extent, counteracts roll and reduces the body lean in a turn. BMW could make the car actually bank up to 5 degrees into a turn, but most drivers use the sensation of lateral force to drive sensibly through corners. Absent sideways forces, they'd go around corners fast enough to slide off the road and experience some or all of BMW's six single- and dual-stage airbags and a body structure that is actually stiffer than the BMW M3 racecar of the 1980s.

The X5 has a new six-speed shift-by-wire automatic transmission (different from previous BMW automatics bearing the Steptronic moniker) that is controlled by what appears to be an aluminum beer tap on the console. Pull back, and you're in gear; slide it left, and it's in automatic sport mode. Or you can tap it forward and back to work the gears yourself. Such a sporting car really needs paddle shifters on the steering wheel. Purists will decry the loss of a manual transmission from this BMW, but it's unlikely that many drivers could get more power or economy out of a manual.

BMW offers adaptive steering as a $1,250 upgrade to the sport package. Steering gets quicker as you go slower, and at parking-lot speeds, it's only two turns lock-to-lock (four turns are typical for most cars). This is a very neat technology, by the second week of ownership; during the first week, you'll clip a lot of curbs learning just how fast it is. But if you want to keep the car's price in check, adaptive steering should be one of the very first options to go. All tires are run-flats now, and BMW has engineered out most of the harshness. I got to experience the run-flat capability first hand, when my test car's tire apparently clipped something sharp on the roadside in Carolina hill country and lost all pressure. The X5 was able to limp for 25 miles to a stopping point where BMW rolled out an entire replacement car, a feature most owners won't get even though the cars do come with four years of TeleService telematics assistance, much like OnStar. The five-passenger production cars also will get space-saver spares.

The upshot: Ride and handling are more like that of a sport sedan than an SUV, which is one reason BMW calls the X5 an SAV, or sports activity vehicle. The other reason the X5 is an SAV is that it's not an off-road SUV in the manner of a Land Rover. It's not even in the realm of an Acura MDX or Audi Q7 although it can ford streams up to 20 inches deep, and the all-wheel drive should get you up most snow-covered country roads. BMW felt the ride and performance tradeoffs would be too great for the seldom-used ability to drive over 10-inch boulders. Should you be pulling a trailer, stability control recognizes that and makes adjustments.

BMW's biggest audio advance in the early 1990s was figuring out how to keep its radios from beings stolen. It was one of the last automakers to offer CD players throughout the line. Now, BMW has a breathtaking array of entertainment technology. Buy it all and you're looking at a cost of close to $6,000.

The baseline audio package comprises a dozen speakers, an in-dash MP3/CD player, and a line-in jack. It's pretty good. The upgraded audio package runs $1,800 and gives you Logic7 surround sound, more amplification, and a six-disc glove-box changer you may or may not want. Then there's Sirius Satellite Radio (not XM), and come spring 2007, an HD radio module, for $595 and $500, respectively—which is twice what they need to cost. BMW will argue that the close competition such as Mercedes charges the same, but today JVC will sell you a complete car HD radio for $200.

An iPod adapter is a dealer-install accessory, and by the time you finish paying the shop charge, you've laid out more than the cost of the iPod. A very nice console mount rear-seat entertainment package with DVD player and game console inputs runs $1,800; you can buy a very good roof-mount DVD player for less than half that, but that's not going to be possible since virtually every X5 comes with BMW's panoramic glass sunroof. A portable DVD player and some Velcro tape would get the job done for about $150.

BMW audio lags behind Mercedes-Benz, Infiniti, DaimlerChrysler, and Honda in several areas. It lacks a hard drive option for ripping and playing back CDs, which makes more sense than an antiquated CD changer; A hard drive lets you store the navigation data while doing away with the need for a separate optical drive only for the navigation disk. And BMWs also have no memory-card slots for music playback, and no USB jack, which could let you access flash drives loaded with music, or (as is the case with Fiats and Alfa-Romeos) connect up every type of portable digital music player, not just iPods.

Virtually every BMW X5 comes with Bluetooth. I tested with a limited number of phones that BMW says are supported, and the X5's Bluetooth linked quickly and also transferred the phone books. Other accessories include keyless access, a power tailgate, running boards, and interior wood trim. None of these are necessary to experience the car's performance or comfort.

At 184 inches, the first-generation X5 of seven years back was just too small for an SUV that was so expensive. Also, it wasn't much bigger inside than the sibling X3, causing buyer confusion. So BMW stretched the 2007 X5 by 7 inches, which makes the X5 the same length as the new Acura MDX, the closest competitor to BMW in terms of savvy design and handling. The Audi Q7 and Mercedes-Benz ML are closer in terms of high cost and cachet. The new X5 gains an inch of room in front, an inch in the second row, and enough space in back for an optional, kids-only third row. But the base weight is barely changed because of engineering touches such as aluminum suspension components and plastic front fenders.

Front-seat passengers live a luxurious life, especially if they opt for the $2,100 power-ventilated comfort seats that blow cool air up your backside and raise and lower the left and right halves of the seat-bottom a fraction of an inch once a minute, the effect being to keep your butt from falling painfully asleep on long trips. Backseat passengers get dual buckets, optional dual-zone air conditioning, and in 2007, optional sunshades (some early kinks need to be ironed out).

One reason only an X5 with vinyl seats costs less than the most expensive MDX ($48,465) is the riot of BMW seating choices: optional leather in four colors ($1,450) or optional high-end leather ($1,000 more), perforated leather (no charge), heated front seats ($500), heated rear seats ($350), and contour seats with lumbar support ($1,200) or active ventilated seats ($1,000 more, but not with the high-end leather), and the third-row seat ($1,700). While BMW seating treatments can cost an extra $6,100, Acura comes standard with three rows of seats, heated leather in front, in beige or black, and calls it a day. BMW's seats are better -- but are they really $6,100 better?

Also up front—lieber Gott—someone finally translated "Big Gulp" into German: The front cupholders now hold, fairly securely, 32-ounce containers. They're located ahead of iDrive and the shifter, which means the containers don't get in the way. You'll find the glove box huge, at least once you figure out that the button down and to the right of the LCD is what opens it.

BMW's online buying site is generally clear-cut. One exception is options configuration: BMW has more options than clickable tabs that fit across a single screen, and it's easy to miss the Next or More button. (The 2007 X5 site isn't live yet, but that's how it is with other BMW sites.) The Owners' Circle is not very good, filled with ads for BMW accessories and services and a lightweight FAQ section; it's not possible, for instance, to see your maintenance records online. But BMW is quick to get back to you if you e-mail a specific technical question.

Customer support should be good. Virtually every BMW comes with four years of TeleService, the BMW help service. And every BMW gets four years of maintenance built into the purchase price.

BMW offers so many options, most of them appealing, that you're going to be paying well into the fifties for even a lightly optioned vehicle. For a moderately well-equipped X5, I'd recommend the six-cylinder with premium package (you won't find many BMWs without it), which includes Bluetooth, leather seats, and the sunroof, for $50,545. If either handling or a superior ride are important to you, get the sport package ($3,600), which gives you the adaptive ride system controlled by the FlexRay bus architecture.

The technology package ($2,600) gives you a good navigation system (good, that is, if you've made peace with iDrive) and real-time traffic data along with the best backup-monitoring system I've seen yet. If you're hauling kids, add the third row seat ($1,700) and backseat entertainment ($1,800). If you want better audio up front, pop for the premium audio system (also $1,800). Instead of the overpriced Sirius and HD radio, you may prefer to go with the iPod adapter; its installed price is set by the dealer. Because BMWs have industry-leading residual values, the cost of leasing a $60,000 BMW may not be a lot different than that of another manufacturer's $50,000 SUV.

Last month, I said the then-new Acura MDX was the best sport/luxury SUV you could buy. Now it's a split decision. Acura remains the value leader among luxury SUVs, if you can think of $47,795 (loaded) as value pricing. The BMW X5 represents the very best on-road, sport/luxury SUV money can buy, and the options are useful and dazzling. On the highway and on back roads, the handling can't be touched. Let's say it's the best $60,000 SUV your leasing dollars can buy.

To read Bill's Acura MDX review, click here.

To read Bill's Audi Q7 review, click here.

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$46,595.00 - $79,590.00

With the X5, BMW delivers a stunning technological statement at a breathtaking price. The new X5 pioneers a 10-Mbps bus that controls the suspension, uses LCD technology that works in sunlight, and adds a Band-Aid fix to iDrive. The X5 is the new standard for upscale SUVs.

FlexRay bus for optional adaptive ride suspension. Performance and fuel economy are both improved. Transflective LCD. Roomier interior, three seating rows.

iDrive remains hard to master. Quirky voice input. Pricy entertainment options. Needs premium fuel. Hard to spend less than $55,000.