The Sky's Not the Limit
Every car company pumps out a convertible. But only BMW's technology-laden 645Ci delivers that folding top as merely an opening act.
By John Tayman

(Business 2.0) – As reams of marketing research reveal, every automobile purchase is intended to be a transformative act. The meek buy speed, the weak seek out strength, and the timid purchase tanks, otherwise known as SUVs. Workaday drones, locked in a cycle of commutes to their office warrens, often buy convertibles—climb in, finger a button, and the roof yawns open, offering the fleeting illusion of freedom. In fact, 296,433 people in this country bought ragtops last year, eager for just such a carefree drive beneath open skies. How alluring is this sensation? Chevrolet now offers a convertible pickup truck. (The prosecution rests.)

The full bliss of going roofless was recently driven home to me in the sublime form of an Atlantic Blue Metallic 2005 BMW 645Ci convertible, perhaps the best convertible now on the market. Among other things, what an $80K sticker price gets you is the ability to enact your transformation on the fly, since BMW's gifted engineers created a top that flawlessly operates even while the car's cruising at 20 miles per hour, allowing it to morph as you motor along, like Chitty Chitty Bang Bang. It's a nice touch, part of the sheer plenitude of technological fillips polished into the 645Ci's slivered shape.

Typically, convertibles are experiments in reductionism, and in one aspect BMW hewed mercifully to type: The company vastly simplified its frustratingly complex iDrive system, that interactive nubbin in the center console that commands nearly every onboard function. In its first iteration, iDrive resembled an officious IT nerd, full of blustery promise but actually more hindrance than help. Simple tasks like changing the radio station required toggling and twisting through an endless cascade of options, tauntingly displayed on the info screen. Thankfully, engineers at the BMW Technology Office in Palo Alto massively tweaked the system. Among other improvements, you can now use the iDrive knob as a simple radio dial, with the screen mutating into a facsimile of a recognizable tuner. Very nice.

Another gift of the Technology Office is the 645Ci's Head-Up Display, which projects information such as speed, navigation cues, and warning lights onto the windshield, where—thanks to a ghostly trick of perspective—they seem to float near the nose of the hood as a hologram. The intent is that the driver never be forced to glance away from the road, and to accomplish this trick BMW embedded in the dash a miniature camera, which blinks up the block of data into the field of view. BMW's Palo Alto office first deployed the technology several years ago, tucked within the helmet of Formula 1 racer Ralf Schumacher; a tiny version of the system projected info onto his visor. A year later, crew members on Larry Ellison's Oracle BMW America's Cup racing yacht wore sunglasses equipped with even tinier, wireless systems, eliminating their need to lurch across the tossing craft to read instruments. (I believe Larry lost, regardless.)

Like most premium rides near the six-figure threshold, the 645Ci also offers the full complement of road-taming technologies, such as stability control, active cruise control, roll stabilization, and the like. BMW goes a bit further, however, piling on active headlights (they swivel as you turn), LED brake-force display (the tiny lights get brighter the harder you mash), and a power-plant breakthrough it calls Valvetronic, which gooses engine efficiency by manipulating the amounts of air released into the valves. BMW refers to this as "breathing," but that seems a bit understated for a 325-horsepower vehicle that can hit 149 mph.

Though it has been in showrooms only a few months, the 645 is a rebirth of sorts, reintroduced from its previous era of 1977 to 1989. Dave Buchko, a company product manager, explained that "the timing was right" to relaunch the 645, by which he meant that the market for ragtops is heating up in the States and there is money to be made—an opportunity recognized by virtually every automaker. Last year 25 different convertibles were available; this year consumers can choose from 35, including a scalped Mini Cooper, corporate cousin to the 645Ci.

Sadly, many of these nouveau topless drive like motorized sardine tins, since they tend to be repurposed versions of their stouter siblings. Lop off the roof of any car and the frame loosens, handling goes squishy, and the altered airflow howls. During its 15-year hiatus, however, BMW reengineered the 645, which is offered as either a coupe or a convertible. For the latter, every detail was tended to, from the aluminum suspension and subframe (which maintains coupelike rigidity without unwieldy weight) to the soft top, graced by a pair of clever rear fins, which nuance the drag and keep the cabin quiet. Another fine touch: The rear window glass can be raised or lowered whether the top is down or up, allowing it to act as a windscreen or cabin ventilator. (About that cabin: swank.)

The top flops down in 24 seconds, just enough time to wheel through the office lot and scoot into traffic. Thumb the "Sport" button and the suspension and steering tighten, gluing the 645Ci to the road. As with the 7-Series, it's almost impossible to break the car loose in corners, and the acceleration is smooth and strong to the point of absurdity—at times it feels as if you're in a simulator, unconstrained by the nettlesome laws of physics. The cliché dictates the use of "flying" in situations like these. And in fact, with the roof down and the windows up and the lone sound being the tuned rumble of the V-8 and the prime sensation being sun and speed and the office falling far behind, well, few appropriate synonyms come to mind. So let's play it safe. Call the experience ... transforming.