It might just be my phone, but whenever I play speed racer and my finger isn't touching the area inside the gray circle, my game refuses to register the input, even if my finger is overlapping with the circle. for instance, if i touch it like the second image shows, Lucia would not move up. My finger has to be perfectly within the circle for Lucia to move up (third image, i'm not good at drawing or erasing circles)
In the middle of speed racer, "am i tapping in the middle of the circle" is the last thing on my mind, yet if it isn't, I get penalized for it by crashing into an obstacle as my character ignore my frantic tapping and doesn't change lines.