In Star Trek III: The Search for Spock, the USS Excelsior is equipped with a transwarp drive.
The Excelsior is introduced as an advanced Federation starship intended to outperform the Constitution-class Enterprise. Captain Styles commands the vessel during its attempt to prevent the Enterprise from leaving Spacedock, and the ship's experimental propulsion system is presented as a major technological advantage.
The transwarp system does not perform as expected. Scotty secretly sabotages the Excelsior by modifying its transwarp coils, allowing the Enterprise to escape. The malfunction helps explain why the supposedly superior ship fails to overtake its older predecessor.
The Excelsior later becomes a successful starship class, but the film's experimental transwarp drive is not portrayed as the standard propulsion system of later Federation vessels. It should not be confused with Voyager's quantum slipstream drive or Discovery's spore displacement system.