I'm wondering, have you done something special like additional filtering of positions and rotations of fingers and palms to get so correct and smooth hand detection? For some reason on my computer the leap motion device data fps is limited at about 43 Hz, and that really hurts detection both with my and other people's projects. However, your app works OK!
Btw, I'd add some transparent texture of dirt and speckles on windscreens to enhance 3D experience. ;)