Vehicle tech has become an increasingly prominent part of the annual trade show, and BMW’s latest innovation has been joined on the show floor by a fully autonomous tractor, built by manufacturer John Deere. BMW has unveiled a new feature that can change the exterior colour of a car with the press of a button, using the E Ink technology best known for being used in the Kindle e-reader. Shown during the CES technology convention in Las Vegas as part of a concept version of the BMW iX, the car is able to switch between white and black finishes at any time.