The Hyposlip Travel system was a type of starship engine invented by the Brothers Hop Pyleen on the planet Rex Vox Jax. (DW: The End of the World)
One type of engine, the Hyposlip 500 lightspeed podule, was greatly coveted by other races in the galaxy. Astro-race pilot Skip Pyleen attempted to sell the secrets of the Hyposlip-500 technology to the Rakkonoids, but was stopped by the Doctor. (DWBIT: Death Race Five Billion)