IIread correctly, none of the devices posted match the one I purchased and used in my old Honda w/o a cup holder. The bottom of the platform has an attached pendulum incased with damping oil. It worked extremely well braking, accelerating, and bumpy roads. Better than a cupholder.
bc misses it as an engineering/physics demonstration. (He gave to relative when he obtained a modern ’bile.)
A little though suggests my description may not be quite correct, but one should understand the idea.