The Infinite Improbability Drive was a wonderful new method of crossing interstellar distances in a mere nothingth of a second, without “tedious mucking about in hyperspace.”
It was discovered by lucky chance and then developed into a governable form of propulsion by the Galactic Government’s research centre on Dick. As soon as the drive reaches infinite Improbability, it passes through every conceivable point in every conceivable universe simultaneously. An incredible range of highly improbable things can happen due to these effects.
It was installed on the Starship Heart of Gold, and both the ship and the drive were unveiled by then-President of the Galaxy Zaphod Beeblebrox.