Semaphores (extendable turn signals)
https://www.youtube.com/watch?v=mm6BFlSZ9DQ
How cool is this
classic safety feature? Forget most modern vehicles with their turn signals integrated in the sideview mirrors. There’s something about a marker stalk flipping out, flashing, and switchblading back into a door pillar that captivates us. Long used on trains and buses, the mechanized signal marker is one of those features that is both eye-catching and useful. It also would be fairly easy to engineer.