Driven: 2016 BMW 640d xDrive Convertible - Driving Take

Before I had driven the 640d xDrive Convertible, I kept asking myself why does BMW insist with shoehorning a diesel under the hood of a full-size convertible. Mercedes-Benz, for example, doesn’t offer such an atrocity in the S-Class Convertible. Furthermore, aren’t convertibles supposed to be a feast of aural pleasure and immersive selfishness?

As I mentioned earlier, I was wrong. Jumping to conclusions is what happens when we overestimate our knowledge. I admit I had made a snap judgment and I was ready to blast BMW for offering a diesel in the 6 Series Convertible, but I will now present BMW with a sincere apology.

You see, car people like you and me expect a plush grand tourer to caress the ears with the brutality of a V8 or the blue-blooded idiosyncrasy of a V12. The truth of the matter is that I wasn’t expecting a diesel to make so much sense in this type of vehicle. And that lack of expectations is the 640d xDrive ragtop’s surprise factor.

Off the line, the 3.0-liter bi-turbo inline-six doesn’t give you the impression that it hurls you forward with the same zeal as an engine running on high-octane jungle juice. Despite the unrewarding sensation, this thing is a tenth faster to 100 km/h (62 mph) than the 640i xDrive Convertible and its more powerful engine. If it weren’t for the alarming rate at which the speedometer’s needle rotates, I wouldn’t have guessed that this thing pulls like a train from second gear upward.

That’s the magic of the BMW TwinPower Turbo diesel straight-six in the 640d xDrive Convertible. Once it gathers a little speed, it keeps on gathering speed without breaking a sweat. It also happens to be unobtrusive when idling or when you’re driving in the city. It does have a problem, though, and that problem is what BMW calls Driving Experience Switch. Yes, it’s those buttons to the left of the gear lever.

Provided that you select Sport or Sport+, everything that’s OK about the engine goes the way of the dodo. The problem lies with how the diesel engine delivers its torque or, more specifically, when. Like with every other oil-burning powerplant, the N57D30T1 delivers the goods in a limited rev range. More to the point, between 1,500 and 2,500 rpm.

When you engage either of the sporty modes, the electronic brain of the car tells the engine and transmission that it’s perfectly acceptable to rev all the way up to the redline, then shift. It’s not, believe me, it isn’t. After it gets beyond the peak torque band, the engine doesn’t feel potent because it gets out of its comfort zone. And that’s the problem with sport modes in diesel-fueled cars, including the ones in this 6er.

I’ve best enjoyed the BMW 640d xDrive Convertible LCI in Comfort mode, chiefly because this is how a drop-top luxobarge should be driven. What about the ZF 8HP automatic transmission? There’s but one way to describe it: smooth and always in the right ratio, like every other ZF 8HP fitted to a BMW model. Nonetheless, it’s not perfect.

The issue I have with this transmission is that the flappy paddles, as expected, have a mind of their own. In manual mode, it’s a hassle to use them. It’s best to leave the transmission do what it does best in Drive and just enjoy the ride. Oh, and another thing: flappy paddles should be fixed to the steering column, not the steering wheel. Signed, everyone who knows a thing or two about driving in a sporty manner.

Now that is has come to sporty driving, I should point out that there’s an elephant in the room. Without any option on it, the 640d xDrive Convertible tips the scales at 2,005 kilograms (4,420 pounds). And as we all know, weight is the biggest enemy of good handling credentials.

But despite its ponderousness, the 6er Convertible in diesel form will happily submit to keen drivers. I was most surprised to discover that it doesn’t feel nose heavy under braking. Although the steering wheel doesn’t give you the slightest idea of what’s happening with the front wheels, the 640d xDrive Convertible also changes direction willingly.

Another highlight regarding driving dynamics is the braking system. Even when you jump on the OH SH*T pedal much harder than you would do in a normal braking situation, the antilock system doesn’t cut in in the same way Kanye West interrupted Taylor Swift at the VMAs. Moreover, brake fade never made its presence felt during my test drive with the 2016 BMW 640d xDrive Convertible.

In the city, the 6er Convertible is unexpectedly civilized to drive and unusually easy to park thanks to the optional rear view camera and similarly optional 360-degree camera system. Be that as it may, the people who have driven the car before me scraped the life out of the 20-inch wheels on curbs and every other imaginable whatnot.

What about ride quality? Well, our car came equipped with Electronic Damper Control and I’m much obliged to tell you that the ride isn’t perfect at slow speeds and on imperfect asphalt. On the open road, though, the ride is as satisfying as a perfectly-crisped strip of bacon.

The bottom line is that the 2016 BMW 640d xDrive Convertible isn’t just surprising. It’s also uncannily good as a grand tourer. It’s has a great appetite for eating up the miles, it doesn’t drink as much as its gasoline-powered siblings, it handles fairly well for its size and weight thanks to the xDrive all-wheel-drive system, and it is comfortable too.

If you’re looking for a convertible GT with the “fizz factor,” you’d better look elsewhere or buy an M6 Convertible with a manual. The 640d xDrive Convertible is, simply put, a GT that will soothe your fevered brow, mile after mile after mile. And that’s perfectly fine by me.