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BMW i8 is getting its roof chopped off – why did it take so long? How does a coupe become convertible?

So we all knew it was coming since 2014, but BMW has kept it a secret up until now – i8 sports car is finally getting its roof chopped off. But why did it take so long? Most supercars get the convertible treatment fairly early in their life time, because hair in the wind thrills are quite popular these days, but BMW i8 seems to prefer taking its time.

Aerodynamics, weight and safety are the main challenges in making i8 coupe into an i8 Roadster. Image credit: BMW

Well, BMW has been working on it for ages, because it is not as easy of a task as people tend to believe. Cars, especially sports cars have to be rigid in order to perform well on tracks and winding country roads. Their body has to reject twisting and bending as much as possible, especially when cornering and for that it has to be fairly strong. Structure of the car is basically two large lumps at front and back of the car connected with floor, chassis, and roof. When one of these elements is lost, something else has to be added to maintain that rigidity.

But the work does not end here. Roof mechanism has to operate in a smooth, dependable manner. Roof has to come off and on while car is moving, which poses some additional challenges. Where roof can be stored? Sometimes there is not enough space for the roof to properly fold down, so the rear seat has to be removed. Whether that is going to be the case with the i8 remains to be seen, but a name Roadster pretty much means that it is going to be a two-seater.

Then there is the trouble with safety. All vehicles have to comply with safety regulations and convertibles, as you might imagine, do not do so well in roll-over crash tests. This means that additional safety equipment needs to be added, such as roll-over hoops or pop-up supports. Both options require some more additional space.

However, the big problem with transforming BMW i8 from coupe to a roadster is going to be aerodynamics. This car is a hybrid sports car, meaning that lots of its performance depend on how sleek it is. There are a lot of aerodynamic elements above the hips of the car – in the area that is going to be removed. It looks like buttresses are going to be replaced with more simple design and the roof itself is going to be a one-piece unit. It means that the car will look a bit like a targa top instead of a real convertible.

So, BMW i8 Roadster took so long, because many problems had to be addressed, such as added weight for structural rigidity, roof mechanism, roll-over protection and aerodynamic performance. Hopefully, i8 Roadster will not gain much weight and will be fun to drive. It will come out in 2018 – that’s when we will get to know how it changed in this transformation.

 

Source: BMW

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