BMW's E Ink Car Wrap Just Took The Leap Into Color

BMW wrapped an electric SUV in e-paper last year — now, for CES 2023, it's looking to bring real color-changing cars to life. The BMW iX Flow seemed, at first glance, to be a normal example of the German automaker's EV. However, a skin of E Ink wrapping the bodywork and wheels could instantly flip it from white through to dark gray.

It built on the same technology we've seen Amazon and others use in ereaders, only on a far larger scale. While a Kindle might have a screen six to eight inches in diagonal, the iX Flow relied on full-width rolls of e-paper almost two feet across. Panels cut from that, tailored to fit the different contours of the SUV, and then wired up to a central controller allowed for a vehicle that could be dark gray one moment, and white the next.

The response proved to be dramatic, not to mention a huge vote of confidence for BMW's Stella Clarke for whom this e-paper wrap began as a passion project. Clarke's endeavors went from a one-woman show to leading a full team now working on E Ink and color-changing, and with the promise of commercialization in the pipeline. I caught up with her at BMW's labs in Munich, Germany, ahead of CES 2023 and the debut of the BMW i Vision Dee which is completely wrapped in color-supporting e-paper.

A faster, smoother electric cuttlefish

The iX Flow still looks remarkable, like something from a science fiction movie brought to life. Clarke and her team built three cars in the end, the first being a wild rush to get it completed in time for its CES 2022 debut last January. Since then, though, they've not been idle.

The current fleet of prototypes has been improved along the way. New controllers and software, for example, have led to much sharper, faster changes and smoother animations. The skin of the iX Flow ripples with grayscale patterns, like some sort of outsized cuttlefish.

At the same time, BMW has been looking at how the cuts can be cleaner and more professional. Even with the body of the SUV broken down into subsections, the resulting strips aren't quite 2D planes. Instead, it's a clever system of slits — laser-sliced courtesy of a huge cutting machine installed in Clarke's lab — which allow the e-paper panels to bend without being interrupted.

Panels now, but spray-on e-paper is the goal

You only see the resulting diamond patterns when you get up near, but the technology is certainly worth a closer look. Another challenge that Clarke and the team has been tackling is resilience: as anybody who has dropped a Kindle knows, e-paper is tough but it's not unbreakable. Road chips can generally be shrugged off — there are parts of the CES 2022 car which have non-functional spots where damage has occurred — but larger impacts will leave sections unable to color-flip.

BMW is looking at bonding the E Ink behind glass, to improve that resilience. However, Clarke points out, the segmented nature of the wrap means individual sections can be replaced rather than the whole thing needing to be redone.

The goal — and it's closer than you might think, Clarke insists — is to make the whole Flow system sprayable. That way, you could simply spray on the e-paper layer, allowing it to coat the contours of the vehicle more naturally.

Color is the next Flow frontier

It's possible, but not quite ready for primetime. Instead, BMW is looking at different ways to commercialize the technology — and to take advantage of what E Ink has been developing, too. One big move there could be color e-paper, moving beyond the grayscale of the current system.

Color ereaders have been around for a while now, but as we've seen with the iX Flow, Clarke's team scales that up dramatically. Basically, different currents applied to the e-paper generate different hues: they're not as vivid or saturated as, say, an LCD or OLED panel would be, but they still have all the advantages of monochrome E Ink. So, power is only required to change the color, not to maintain it, and it's all supplied on a flexible backplane.

Color-changing BMW cars are one possibility; while you might expect that to be hugely expensive, Clarke suggests that it could actually be more in line with a regular wrap. However the team has also been working on e-paper wheels: think spinners, only instead of a physically moving disc, each of the spokes gets a panel of color e-paper.

Spinners meet 2023

The result is eye-catching in the best possible way. BMW's prototypes are big, dished wheels: all the better to show off the color panels. However, there's no reason that the e-paper couldn't be applied to narrower spokes. Since E Ink's technology is such a power miser, you could even collect enough juice to handle the hue changes by harnessing the rotational forces of the wheels themselves.

Again, the goal here is not just a flashy tech showcase for the Consumer Electronics Show, but something which BMW could commercialize if the response is there. Clarke says that, after the positive reaction to the iX Flow, there's also been interest from within other departments at the automaker about how e-paper could be used for interior controls and panels.

That sort of judicious application is already playing out elsewhere at the automaker, even if only on other concept vehicles. The BMW i Vision Dee, also unveiled at CES 2023 this week, uses color e-paper too. The body surface of the electric sports sedan is divided into 240 different E Ink segments, each of which can be controlled individually and switched between 32 different colors. Sub-sections in its fascia, around the rear lamps, and in panels around the side windows support a resolution that can not only show animations and patterns but can also be used to display things like parking permits, with BMW envisaging the driver's credentials automatically appearing depending on where the EV is.