The red O served to help people pronounce the name correctly (Mo-bil, not Mo-bile).
Thank a type designer who doesn’t settle for just “standard” but knows how to choose, create, or modify an existing typeface to be a memorable and expressive brand mark.
Ferrari, put my son’s prancing horse on your cars. It will bring you good luck.
It is a parallel between the modern and the old, some of the slogans dating back to the 40s and 50s.
None of the options “captivated anyone” so it came down to “which was the least awful.”