Let's get it out of the way right now.

BMW AG’s all-new ’06 M5 is, pound-for-pound and dollar-for-dollar, the nastiest but most delicious vehicle on the globe.

At $81,895, the car hardly is inexpensive, but easily rips from Chevrolet’s $65,000 Corvette Z06 the year’s best-performance-for-the-money crown, despite costing 15 grand more.

That is because the Z06 is strictly about brute power. You get 505 horses from a bellowing, bored-out-to-a-fare-thee-well 7L small-block OHV V-8 and 0-60 mph (97 km/h) in 3.7 seconds.

All-new M5 is wildest BMW ever.

With the ’06 M5, you get a titanically tech-rich and tidily sized 5L DOHC V-10 that revs to 7,750 rpm with an improbable lack of inhibition to generate its 500 hp, the 0-60 mph bolt in a blurring 4.5 seconds – as well as five roomy seats, a grandly outfitted interior and the kind of everyday refinement and driveability that just about anything approaching the M5’s performance quotient cannot hope to match.

For all this, but particularly the new M5’s blistering, insanely accessible performance, the competition – not that there really is any – should be very afraid.

BMW’s all-new M5 is, from stem to stern, one of the most spectacularly complete cars in memory, a scintillating sport sedan with almost no foibles or flaws.

This 5L DOHC V-10 has to be one of the industry’s all-time gems. From the now-signature M-engine individual throttle for each cylinder to the 17% lighter valvetrain (vs. the previous-generation M5’s 4.9L V-8) to the VANOS variable valve timing system specially pressurized to speed response, the overwhelming design priority was to derive power from high rpm.

So explosive is the horsepower onslaught that one never gets the chance to ponder the V-10’s comparatively meager – if 383 lb.-ft. (519 Nm) of twist can ever qualify as meager – torque production. Few road-going engines can so quickly swing the tach needle or propel a 4,012-lb. (1,821-kg) vehicle so effortlessly to silly speeds.

The other needle that moves rapidly belongs to the fuel gauge, unfortunately. The M5’s 12 mpg (19.6 L/100 km) city/18 mpg (13 L/100 km) highway rating earns it a $3,700 gas-guzzler tax.

But actually achieving those numbers would be a treat compared with the shocking real-world consumption. Working the car somewhat aggressively drained a half tank of the very best post-Katrina unleaded in less than 100 miles (162 km). Our on-the-fly calculation was something on the order of 8 mpg (29.4 L/100 km).

The engine’s lightning throttle response can be adjusted, like many of the M5’s electronic systems, with the exquisite MDrive system that allows the driver to coordinate the settings of the throttles, the SMG 7-speed sequential manual gearbox, the electronically controlled damping and the Dynamic Stability Control system.

BMW engineers say there are 279 possible combinations. Once the owner chooses a preferred setting for each individual variable, this combination is programmed for instant selection via the MDrive button on the steering wheel. Hit the button and the one ideal combination is activated. Quite nifty.

As much gushing as the M5’s stupendous powerplant deserves, the chassis is far from shabby, either.

The 5-Series range enjoys an aluminum-intensive front strut and rear 4-link suspension, and the M5 improves on that already high standard with a specific front subframe and specially selected tuning hardware.

The rear gets similar tuning upgrades, and each corner is fitted with the electronic damping control system that provides three damping modes. Whatever mode is selected, the system continuously strives to adapt the selected general mode of damping firmness to real-time driving conditions.

Like everything else about this car, the damping and general handling are crushingly effective. The M5 devours corners at speeds one is convinced defy physics.

Include in this formula the superbly tuned electronic stability control and the giant, cross-drilled “compound” disc brakes with abilities that only Michael Schumacher would be brave enough to push to the limits, and you have one immensely sublime chassis.

The day the M5 is driven in the Hudson River valley, it is raining heavily at a temperature that at times produces a half-sleet mix.

Not only does the M5 grip the tarmac in an unholy fashion, full doses of the V-10’s thrust when exiting corners do nothing more than wag the M5’s tail as the DSC system precisely determines the amount of available grip and meters the V-10 accordingly. Testers universally agree it is no mean feat to distribute the V-10’s might in ideal conditions, let alone these. None trust their right foot enough to fully disarm the stability control in an attempt to dole out 500 hp on slimy pavement.

There is one chink in the M5’s imperturbable armor, and it is a minor one: the Sequential Manual Gearbox.

The 7-speed SMG is the first of BMW’s automated manual transmissions (there is no clutch pedal) to be designed specifically as a clutchless manual. All previous SMG efforts have been “standard” manual transmissions adapted to SMG clutchless design – and have not enjoyed universal acclaim.

If one must have seven speeds, there is method to this madness. After all, a seventh gear would complicate manual shifting in a conventional H-pattern that already can be crowded and confusing with six forward gears.

And to extract the most from the high-revving V-10, engineers apparently deemed seven closely stacked ratios a necessity.

But the M5’s 7-speed SMG, although spectacular in many situations – automated double-clutching and revving of the engine for high-speed downshifts is a particularly thrilling parlor trick – and acceptable 90% of the time, occasionally is jerky and reluctant.

There are six distinct shift-speed and abruptness settings for when one wants the SMG to shift in fully automatic mode, but the only one that seems acceptable is the quickest.

Gears can be sequentially selected manually, of course, via steering wheel paddles (which are confusing) or by the beautifully shaped and lit stubby lever on the console.

Although countless hours of engineering toil went into the 7-speed SMG’s development, BMW, to its credit, acknowledges SMG may not be for everyone.

For some mystifying reason, U.S. intenders were particularly adamant about the availability of a conventional 3-pedal manual transmission for this most super of all M5s, and BMW says a 6-speed manual will be available in the fall of 2006.

As if to underscore its bounty hunter performance, the new M5 also fronts dead-serious interior fittings commensurate with the car’s price, a point still lacking in some standard 5-Series models. The M5 gets BMW’s best leather and excellent genuine brushed-aluminum or wood trim.

The gauge package, in particular, is stunning, thanks largely to the unique “variable” tachometer reading that progressively raises the available redline as the engine reaches appropriate temperature.

Ancillary lighting is equally rich. One of the few options, the $1,000 head-up display, is the first HUD that justifies its existence. The HUD can be configured to show gear position and is encircled by a representation of the tachometer so it is easy to keep abreast of just how furiously the V-10 is spinning.

Our final assessment: But for the SMG’s minor imperfections, the M5 is the world’s best performance car. Not as crass or as unwieldy as the Corvette Z06, infinitely more emotive and engaging than Mercedes-Benz’s fast but indifferent AMG cars, quicker yet more useful than a Porsche 911 S.

We’d sell our souls for one of the 2,000 M5s BMW plans to sell in the U.S. annually. Given the M5’s comprehensively thrilling performance and personality, we’ll wager there may be some soul-selling just to be one of those 2,000.