Not long after I escaped the steaming, teeming riverboat city, I crossed the Arkansas state line and the rain hit. The cooling reprieve from a blistering July afternoon brought reminiscences of relaxed drives in the country.

My reverie was abruptly ended by a cacophony of flashing lights, harried braking and a long line of traffic that wound around a distant curve. After a few minutes, an ambulance flashed past in the opposite direction. A short while later, a driver who had seen the problem, and decided to turn around, rolled past me with her window down.

"It's bad," she said. "Terrible."

I called the newspaper to tell them I'd be a little late and was told that a car-bus accident had left two dead. Then I glanced over at the BMW X5's navigation system and began plotting my escape.
 
I whipped around, went a couple miles south and then jogged west, soon finding myself traversing unfamiliar roads.

In about 10 minutes, I was on muddy, crowned roads and soon discovered the value of the BMW's xDrive, which adjusts front/rear torque proportioning according to road and driving conditions to improve traction and handling.

Whether going around a slippery curve or working down a steep, muddy hill, xDrive seems proactively to sense when the vehicle might lose traction and adjusts driving torque to front and rear wheel wheels accordingly. In the instant I felt the slightest slip, the vehicle brought itself under control.

I motored on in quiet comfort. Inside, the X5 is impeccably designed and built. The ergonomics are superb, the materials first rate and fit and finish throughout are world class.

I turned on some quiet classical music and spent about 15 minutes enjoying the gentle rain as I discovered an abundance of pastoral settings around Doddridge, Ark., Soon, I was back on the highway, past the tragedy.

Once again, I had discovered some more to like about a vehicle that began to grow on me the moment I spotted the unmistakable and lovely BMW gull-wing look of its nose.

This is such a complex, refined machine that I could literally go on all day about it. To conserve the time of my friend Julia Mickinney, a retired English teacher who insists it is but good manners to read every word that a friend takes the time to write, let me try to put this into a nutshell.

The X5 takes all the best of a sport utility - commanding driving position, the feel of muscular safety and substance - and combines it with what you'd expect from BMW: Exhilarating performance, sophistication, luxury, quality you can see and feel.

As nuts go, that's more coconut than pecan but it gets the point across.

Built in Spartanburg, S.C., the X5 has been a huge success since its introduction in 2000. It's been a favorite of auto reviewers and consumers, frequently winning awards for style, performance and quality. It has been Kelley Blue Book's leader in residual value.

The vehicle has become an icon of quality and accomplishment not only in North America but around the world. 500,000th X5 recently rolled off the line in Spartanburg. Industry buzz is that a makeover is coming for 2006, but nothing official has come out of BMW.

The X5 comes in three models: X5 3.0i, powered by BMW's inline 6-cylinder engine and with a base price of $42,395 including destination charge; X5 4.4i, with a Valvetronic 4.4-liter V-8 ($53,495); and a the flagship, a high performance X5 4.8is ($70,795).

Our tester was a base 3.0 that went past $50,000 with options such as navigation system and dual-panel Panorama moon roof.

We found the 225-horsepower inline 6-cylinder unit to have plenty of power for daily driving. Combined with the optional a 5-speed version of BMW STEPTRONIC automatic transmission, the powertrain was smooth and quite fast.

I'm still puzzling over the sports shifter's oddball control method. The old math teacher in me understands that for every operation there is an inverse operation. You can add, or you can subtract. You can multiply or you can divide.

From equations to chemical reactions , we know they are true if the read the same backwards and forward.

But why BMW chose to activate upshifts by pulling back and downshifts by pushing forward, when every other sport shifter on the planet works the opposite, simply escapes me. If you've ever had a Triptronic shifter in another vehicle, this one will drive you nuts.

On the other hand, I think the 6-cylinder engine is the right size for this vehicle, at least until BMW decides American consumers are ready for the diesel X5, a big seller in Europe and Australia.

With the six, we averaged around 22 mpg, and that's a good thing. The X5's 29-gallon fuel tank can cost you $70 or more to fill at today's prices.

About 40 percent of American buyers are opting for the Valvetronic V-8 engine, new last year. This engine delivers 315 hp, and also achieved EPA fuel-economy ratings of 16 mpg city/22 mpg highway.

Valvetronic is a patented BMW system that varies valve lift to control engine power. Instead of a conventional throttle, Valvetronic varies valve lift all the way from a minuscule 0.3 mm (for idling) to a high 9.7 mm (for full-power operation). Thus eliminating the "pumping losses" associated with throttles.

The X5 4.8is takes the Valvetronic power concept to an even higher level, employing a larger bore and stroke to obtain a displacement of 4.8 liters. The result: 355 hp, and 360 lb-ft. of torque . The 4.8is reaches 60 mph from a standstill in just 5.9 seconds and has an electronically limited top speed of 149 mph.

That's faster than I need to go, but if I decided to go that fast, I'd feel quite comfortable doing it in this vehicle.

Typical for German makes these days, the X5 had its little glitches. One power window didn't work. A warning buzzer gremlin occasionally decided the driver's seat belt fastener was unfastenbed when it wasn't.

Bottom line: It's easy to see why many enthusiasts consider this the best SUV of all.