Designing for Style© by Lyn Zbinden
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BMW i8 – Production vs. Concept
The BMW i8 began with the launch of Project I, the reinvention of urban mobility. Everything about this car is designed to be functional and nimble. The extensive use of lightweight materials from the ultra-thin seats to the flat screen instrument panel makes this vehicle look void of anything that suggests it’s not responsive. All of this is made possible to increased use of polycarbonates, carbon fibre and other exotic materials. The car was designed as a model for fuel efficiency and a showcase for BMW’s utilization of cutting edge technology.
The extensive use of glass, from the doors, engine bay, panoramic roof and decklid is especially intriguing. The shapes are very expansive, curvy and seem to showcase glass as a structural element. The door lifts out and up with one-hand ease, yet it shuts with a convincing snugness. Looking at the BMW i8’s sidelites pictured below, notice that the sidelites are two separate glass panes. The lower lite is glass and dynamic and rolls into threshold much like an earlier BMW Z1 concept. The upper stationary lite is framed polycarbonate. The glass/polycarbonate is framed to provide its structural integrity. This is because a polycarbonate side window will not perform to desired expectation if the vehicle is mobile and unsupported. The frame around the window adds rigidity.
The extensive use of glass/polycarbonate gives an eye popping view from inside or outside of the cockpit. The side glass on the concept version is amazing. It shares the same technology with the smartphone screens, very thin and light, but strong and actually flexible, less than 3mm thick, a conventional glass sidelite is 4mm thickness and heavier given the same area. The trick in achieving comparable weatherability with glass is in the plasma coating technology BMW uses on two-component (2K) injection molded PC windows. Using polycarbonate resin, which is an engineering thermoplastic, characterized by outstanding mechanical, optical, electrical (diverse antennas) and thermal properties, BMW anticipates capturing a reduction in weight in comparison to comparable glass applications by as much as 33%, while delivering a high-quality optical appearance and scratch-resistant surface.
The Vision concept features a glass nose-to-tail roof and glass butterfly-opening doors. Glass offers good structural qualities and a market niche. The glass nose is a similar Pininfarina 4/5 styling cue, offering a glimpse into the well-appointed engine compartment. In the view below you are seeing the power generation unit.
The panoramic roof is always an eye catcher
Panoramic benefits include:
Styling flexibility & design selections
Simplified assembly processes
Improved side-impact crash safety
Options to integrate additional functions or interior components
Decreased noise levels
The radically styled Vision concept was the ultimate expression of the flame-surfacing approach to styling championed by former design Chief Chris Bangle. Flame surfacing is characterized as a technique used by BMW designers to create an appearance that is supposed to look like flames licking the car. They use convex and concave curves that suddenly turn into sharp lines to create a fire-like effect. One of the most evident examples of this design language is the 1 Series. If you look at the side of the car, you can see a swoosh toward the bottom of car that swings upward to the rear and it has a sharp line at the shoulders. Now there’s a successor – layered surfacing – initiated under new group design boss Adrian van Hooydonk. While emphasizing that flame surfacing is not consigning to the history books, BMW says, “It has been developed to enhance its effect further.” The idea is to smooth the shutlines and joints within the body for what van Hooydonk describes as “a more cohesive and harmonious appearance”. Body surfaces are layered on top of each other in a move that is also claimed to improve aerodynamic efficiency without the requirement for any additional body elements.
“By using the structure of the surface without adding any appendages, we’re able to optimize the airflow,” says van Hooydonk. The prime examples on his super-coupe concept, he says, are the A-pillars, which channel the airflow at the front in the same way as the wing-profile rear lights. This design philosophy is executed beautifully on the i8.
Concept Gen One
The first generation concept featured a two piece sidelite configuration made of polycarbonate and glass. Also there is no fixed vent at the sail portion (where the A Pillar, belt line and sidelite meet) just a side view mirror affixed to the A Pillar.
The top vehicle is probably a second or third generation concept, further along in the design phase than the Gen One. Noticeably absent is the two piece window. The bottom vehicle as you can see is a more conventional design. The B pillar is more vertical featuring a roof mounted antenna. It is one piece construction made from glass.
I am always asked “Can we do this, can we produce a polycarbonate sidelite?” The answer is yes! We have the technology, we know the weight benefits and the cost drawbacks, we know the Federal safety standards needed to be met, and we just haven’t got there yet. Will we? I believe so. I believe that manufactures will overcome the billowing glass with some type of structural reinforcement, and I don’t seem to be alone in that thought. Large companies likes SABIC, Exatec and others have plants set up and are funding research with millions of dollars and euros.