If you believe what some automakers tell us, designing and building a car is only slightly less difficult than achieving world peace. A constant battle between the design and engineering departments, the process seldom completely pleases one division or the other. And that’s just for sedans and wagons. Convertibles really make sparks fly.
However swoopy and graceful the open-top models, they are inherently weaker structurally than their tin-topped siblings. Spin a shoe box with the lid on, then do the same with the lid off and you’ll have a fair idea of what cutting the roof of a car does to its rigidity. When a car is less stiff, all sorts of things detract from its prime function of transporting people in safety and comfort.
So for every one with an idea of how the next generation convertible will look, two engineers will be racking their brains
working out how they are going to make the thing get down the road in a safe, reliable, and hopefully fun way. And if it looks good too, well, that’s a bonus.
Bearing all that in mind, the BMW 645Ci Convertible is a reasonable achievement. It takes on the 645i Coupe’s radical profile and adds a cloth-topped design that works equally well with the roof open or closed. Not sure it works quite as well as the SL500 Mercedes-Benz design, but its fluid shape and four-seat flexibility set it apart enough for it to appeal.
Where the Mercedes scores over the BMW is in its super-solid structure. It doesn’t matter whether its metal roof is in place or stowed in the trunk. It doesn’t shiver and shake when it hits bumps or holes in the road. The same is not 100 percent true for the fabric-roofed 645Ci. You notice it only when in full gung-ho mode on a bumpy back road, but the fact is it’s there.
That said, the design has several sweet features. All the glass in the cabin, including the rear screen, is completely separate from the roof, allowing fine metering of the air passing in and through the cabin. It’s a relatively small point on paper, but in the real world this is a useful feature.
In fact, all the phrases you want to see on a sports car are present and correct on the 645Ci: a big, throaty V8 engine; rear drive; and a sub six-second 0 to 60 mph time. You can add interesting extras, such as handsome, 19-inch wheels and active steering, which makes driving feel more like playing a video game than navigating a couple of tons of steel and glass down the road.
The interior offers a comfortable amount of room in the front seats and, particularly with the top down, enough space in the back to not feel too guilty about asking someone to sit there for more than a few blocks. You wouldn’t take the family vacation in the Ci, but you also wouldn’t think twice about four of you going out for lunch in it.
The other joy of the cabin is the simplified i-drive feature control system. Maligned almost as much as the contemporary styling, i-drive gained a reputation when it debuted in the 7 Series for being more difficult to use than a blank keyboard. But for the 6 series, this fabulously complicated confection, which could make turning on the air conditioning feel like launching the space shuttle, has come down to Earth. Even so, every time it looks like rain ahead, you can’t help but be thankful that the roof controls are separate.
Performance of the 645Ci is highly respectable. Even though it tips the scales at around 400 pounds more than the 645 coupe, thanks to the roof mechanism and body strengthening, it has enough shove at all speeds to never leave you feeling shortchanged in the engine department. No doubt the future holds an M version, which will become the must-have choice, but for now it’s more than just enough.
Handling, despite the occasional flex in the chassis, is excellent. With the standard Active Roll Stabilization system keeping everything on an even keel, there is little to worry the driver or passengers as you power to your destination. As with most BMWs, balance and poise are as delicately adjustable with the throttle as with the steering wheel. It’s a genuinely unique side of the BMW character that keeps customers coming back.
In terms of competition, there’s little like the 645Ci for the money. There’s the Audi S4 convertible — a more conventional, practical but equally performing alternative. Otherwise, there’s little else to consider it against in the under-$100K, four-seat convertible market. BMW 645Ci prices start at $76,900.