In biology it's called "convergent evolution" -- unrelated organisms separately evolve the same trait.

Birds and bats both have wings, for example, but they evolved from very different lineages. Like humans and other primates, Wall Street bankers have 10 fingers and toes, even though they evolved from disgusting, invertebrate slugs.

In the last couple of years, BMW, Porsche, Honda and VW/Audi have all separately arrived at a wagon/coupe/crossover solution because they are all dealing with the same retail ecology. For one thing, many buyers are maturing out of their cretinous SUVs and crossovers. They want something sporty and coupe-like but they still want the commanding outward view and some modicum of utility.

For another: Product development systems are now so streamlined that carmakers are able to cheaply riff off established chassis, offering subspecies of vehicles to make sure they have something in the showroom for everybody. BMW, for instance, has grafted a fastback rear end to its 5-series sedan to make the 5-series GT. To me it looks like the car has developed an egg sac.

The latest and, I assert, the greatest of these efforts is the Acura ZDX, a ferociously dynamic, red-in-tooth-and-claw styling exercise from Acura's Torrance design studio.

If only this major-league body didn't have a minor-league chassis to go with it.

This is the first Acura designed, engineered and being built in North America (Alliston, Ontario. That's Canada. Can you smell the bacon?).

The ZDX's Yankee designers -- all trained at Art Center in Pasadena -- have managed to transcend the dictates of the marketing weenies to make what I think is a lasting contribution to the designed world. Forget the modernism of the Tokyo skyline. The more you look at this thing the more you expect it to have a license plate from Alpha Centauri.

Based loosely on the mechanicals of the MDX, the ZDX's roofline is 6 inches lower, its ultra-rakish coupe profile limned in a dark-tinted glass canopy that stretches from the hood all the way to the taillamp assembly. The sides of the greenhouse taper inward dramatically to the rear, creating outrageous rear haunches that might as well have been lifted from a Paris-Dakar Porsche. The side window daylight opening (the DLO in industry parlance) is sports-car narrow, slitted and menacing -- the effect you'd get if you spit in Clint Eastwood's eye. To further de-emphasize the four doors, the rear door handles are hidden in the corner of the DLO.

The whole thing is as taut and engaged as a crossbow aimed at your temple. Nifty.

Five years ago, such a car would have remained an auto-show concept, a turnstile queen, virtually un-buildable. The rear quarter panels, with their complex hyper-paraboloid shape and deep "draw" -- which is to say, the depth of the metal-stamping form -- would have been too difficult and expensive to manufacture. Advances in tooling technology have changed that.

The ZDX's glass-to-glass panels around the panoramic roof mean there's hell to pay in fit and finish, wind-noise attenuation and weatherproofing. This is not an easy car to build.

Nor is it cheap to build. Acura lavished a lot of money on the interior, including couture-quality leathers on the dash, seats and doors; a suede-like headliner material; and a fully finished cargo area with plated metal handles and high-quality carpet. Another interesting bit of hardware is the new "monolith" center control panel, a bank of black switches that remain dark until the relevant systems are activated. It kind of reminds me of the "dark panel" feature in Saabs.

Under all its exotic skins and complex surfaces, however, the ZDX is a more-or-less conventional, and less compelling, Acura crossover.

Behind the Cyclops visor of a grille is the company's sweet, tractable 3.7-liter, 300-horsepower V-6, married to a new six-speed automatic transmission, and the so-called super-handling all-wheel drive. Ordinarily, 300 hp, six gear ratios and AWD would add up to significant off-the-line thrust and punchy passing power. Here, not so much, thanks to the Acura's galling curb weight of over 4,425 pounds.

Who knew pretty weighed so much?

This tonnage can make the ZDX's performance feel downright dreary. Acura says the car's 0-60 mph acceleration is less than 7 seconds. That seems to be wishful thinking, based on my test drive. Also, at Los Angeles freeway speeds, the ZDX feels a little out of breath when passing.

And, while none of the competitive cars -- the Infiniti FX35 or BMW X6 included -- gets any better than criminal mileage, the Acura's 16/22-mpg city/highway rating isn't anything to write home about. At that rate Acura might as well buy Ford EcoBoost crate engines.

All the chapter-and-verse refinements from Acura are here -- well-isolated chassis, deft and well-strung suspension (struts and multi-links), powerful brakes. But it doesn't quite add up to driving arousal.

A bit of theater: In the center console is a big rotary dial, the switch for the Integrated Chassis System. This two-mode system (Comfort and Sport) stiffens the suspension and dials back the power steering boost for sportier steering feel. But since the steering ratio remains the same, and the suspension remains fairly limber even in Sport, the ICS seems like just another excuse for a tasty acronym.

The trade-off in these four-door coupe crossovers is, naturally, rear headroom, which is sacrificed to the gods of swoopy rooflines. Such is the case with the ZDX. If you're sitting in the back, the roof doesn't so much seem to slope as fall in, coal-mine style. As for the cargo space, I was able with some difficulty to get my full-size standard poodle in the back. He's still not speaking to me.

Highly evolved on the outside but relatively un-morphed mechanically, the ZDX's main compensation is its outrageous looks. For active empty-nesters, DINKs and every-other-weekend parents, the paucity of rear headroom and cargo space will be no problem. For sports-coupe enthusiasts, they might want to wait for the inevitable performance variant to come.

For the rest of us, we can just look and enjoy.