In the gambling and entertainment city of Las Vegas, audiences flock to see famous magicians. So it seems par for the course when a large, angular car slowly changes from white to gray and then, finally, to black. But how does it do it? The SUV, which is on display at the annual CES trade show, is surrounded by amazed onlookers who want to see this magic close up.
Yet it isn’t some fancy Las Vegas magic trick or illusion behind the vehicle, but rather real engineering work. At the CES in January 2022, car manufacturer BMW proudly presented its “BMW iX Flow featuring E Ink”—the world’s first car that can change colors. So if the driver is in a dark mood, they can drive to work in a black car, or in a white one when they’re feeling light and airy—warning their colleagues before they even step out of the vehicle.
This is made possible by the technology of the company’s cooperation partner E-Ink, which is currently used in a similar form in e-book readers. Several million microcapsules are embedded into the surface coating of the car body. Each of the microcapsules contains positively charged black pigments and negatively charged white pigments. Depending on the polarity of the electrical field, either the black or the white pigments migrate to the upper side of the microcapsules—turning the car either black or white. No energy is needed to maintain the color, and it draws just a little current when the color changes.
The woman behind this technical magic trick is Stella Clarke. The project director and engineer explains the big advantage: light and dark colors absorb heat differently. On a hot sunny day, a white surface, which reflects light and heat, can prevent the car from heating up too much. Conversely, on cooler days, a dark-colored car can absorb more warmth from sunlight. “In both cases, a targeted color change means you can turn down the heat or the air-conditioning inside the vehicle,” Clarke says. This saves energy—which means that, for an all-electric vehicle, changing the color could also increase the car’s range.
Additionally, cars could use the e-ink technology to communicate with the outside world. In a snowstorm, cars could glow red to be more visible to other drivers, or, in the city, the color green could signal that a car-sharing vehicle is currently available.
There is further potential beyond the automobile industry, as well. This technology is already built into the majority of e-readers because it saves power. It can also be found in supermarkets, where it has replaced analog price tags on the shelves. Similarly, e-ink is sometimes used in bus and train stations, not to mention for art installations. Add colors to it and the possibilities seem almost limitless—for instance in smartphones. There are already a few smartphone models that use e-ink technology on secondary screens on the back of the phone. And when the models in Las Vegas start wearing e-ink clothing that magically changes colors on the catwalk, that will be a show worth betting on. Abracadabra indeed!