Instrumented Test
Since the 6-series returned from hibernation more than a decade ago, BMW’s big convertible has occupied an enviable spot in the motoring pantheon in that it has few direct competitors. Mercedes-Benz’s S-class cabriolet is significantly more money, while the E-class convertible offers little in the way of grand-touring pretense. The Mercedes SL lacks rear seats, and Porsche’s droptop 911 Carrera is, again, a fair piece more expensive. In fact, Ford’s Mustang and Chevrolet’s Camaro are perhaps the closest analogs to this 6-series, price notwithstanding.
Admittedly, the brutish, gregarious, and far cheaper Yanks don’t offer an interior anywhere near as nice as the BMW’s. In fact, we’d go so far as to say that our 640i test car’s cabin was as nice a place as we’ve seen in any Bimmer that wasn’t wearing Alpina badges. We were especially smitten with the immaculate veneer applied liberally to the console. BMW calls it “Fineline,” but it looks for all the world like some sort of zebrawood. Whatever tree the stock is cut from, the effect is modern and refreshing in an age when every other car seems to be festooned with some sort of carbon fiber.
As is par for the course with grand-touring machines, the back seats are reserved solely for the legless—or at least the footless. For those who dare sit in the back, ingress and egress are best attempted with the top down. Speaking of the top, with it raised, the BMW wasn't much quieter in the cabin-noise department than the burbly Mustang GT convertible, measuring 68 decibels at a steady-state 70-mph cruise; we measured the Ford at 70. The Mustang also offers a manual transmission. If you require a clutch pedal in your 6er, you’ll be leapfrogging all the way up to an M6.
Otherwise, you’re left with the ubiquitous and generally excellent ZF eight-speed automatic, controlled by paddles or BMW’s still-irksome, fiddly electronic gear selector, a shifter that offers no distinct advantage over a standard PRNDL arrangement. Receiving 330 lb-ft of peak torque from the 315-hp turbocharged 3.0-liter inline-six, the ZF routes torque to the rear wheels, resulting in a quarter-mile sprint of 13.6 seconds and a zero-to-60-mph run of 4.9 seconds. Those figures are 0.8- and 0.3-second behind the twin-turbo, V-6–powered Mercedes SL400 we tested, a car that has 329 horsepower and 354 lb-ft and was significantly lighter. It’s also slower than a manual Mustang GT convertible by 0.4 and 0.2 second.
Okay, we should probably put the kibosh on the pony-car stuff. Few people outside of an oddball collection of semi-wealthy gearheads will ever cross-shop the 6 and the Mustang or Camaro. We know a few of those guys, but they’d be just as liable to buy both cars. Or lust for one of the Americans but purchase the BMW due to some other pressure. Conversely, they might long for the Bavarian but decide that the extra 40 to 50 large could come in handy if young Jordan decides to pursue that MFA in artisanal glazing.
But what the Mustang and Camaro comparison does do is cast the BMW’s value proposition in a rather harsh light. See, the big Bimmer isn’t exceptional in any one area. A Benz—any Benz—of remotely comparable price is more comfortable for long-distance travel. BMW’s own M235i wins our hearts when it comes to the brand’s traditional handling virtues, especially in the area of steering feel. Stretch the pocketbook and the 911 offers more comfort and more playfulness.
Our car, equipped with BMW’s M Sport package, offered what seemed to be a slathering of faux sportiness. The turbocharged six remains a sweetheart of an engine, but it feels slightly overwhelmed by the 640i’s two-plus tons of mass. On the skidpad, the big 6 managed 0.86 g on grand-touring summer tires, but during the same testing session, a lowly Chevy Malibu pulled the exact same number on all-season rubber. Meanwhile, the ride felt unduly harsh, even on smooth freeway stretches. Flipping the car into Comfort+ mode ameliorated the ride-quality issue, but we liked it when BMWs had just one suspension mode: BMW. That one tended to work remarkably well in all conditions. Also, selecting Comfort+ leaves us feeling like retirees in Boca.
What, then, is the 640i convertible’s place in the scheme of things? Why, it’s a profiling machine: all long hood, short deck, and a great dollop of huge bigness. The thing’s a hundredweight of Bavarian presence built specifically for Santa Monica or South Beach. Or perhaps as a sunny-day oligarch’s car in summertime Sochi. Regardless, it’s an automobile for a particular person—one who would rather not be seen in a Camaro or a Mustang, and who just might prefer Comfort+.
