"all the world's a stage and all the men and women merely players, they have their exits and their entrances and one man in his life plays many parts, his act being seven stages... " - william shakespeare
The Dauntless-class isnt strictly a federation starship - The Dauntless was an alien vessel disguised as a Starfleet prototype starship of the Dauntless-class. It employed quantum slipstream technology, which allowed it to go higher then the standard Starfleet warp scale. Although created by alien technology, the ship was modified to resemble Federation starships on the interior and exterior by the means of particle synthesis.
The Dauntless was equipped with an experimental quantum slipstream drive capable of propelling the ship over fifteen light years in only five minutes; it was capable of traveling from the Alpha Quadrant to the Delta Quadrant in four months.
the crew of voyager discover what they thought was a federation ship
This translates to an average cruising speed of 28 light years per hour, or a burst speed of up to 300 light years per hour.
In mid-2374, while still stranded in the Delta Quadrant, the U.S.S. Voyager received a transmission from Starfleet Command via the ancient Hirogen communications network. Although the message contained a number of unencoded personal messages, there was also an encrypted file that the Voyager crew was unable to open.
On Stardate 51978, Voyager encountered an alien named Arturis who had a gift for translating languages, both verbal and computerized. He easily decrypted the mysterious message, which gave a set of coordinates near their current location. Upon arrival, the Voyager crew discovered the advanced Starfleet explorer, Dauntless.
the dauntless fitted with the experimental quantum slipstream drive
Incorporating technology that promising a faster trip home, the Dauntless proved to be an elaborate trap set by Arturis to arrange for the Voyager crew's assimilation by the Borg. Arturis's race had been recently assimilated by the Borg, and Arturis blamed that event on Kathryn Janeway's short-lived alliance with the Borg against Species 8472.
Ultimately, Voyager eluded the trap, and Arturis was left stranded aboard the Dauntless as it entered Borg space, where he was presumably assimilated.
Voyager later used the slipstream technology examined aboard the Dauntless to construct their own makeshift slipstream drive, which eventually propelled them over 300 light years closer to home before it burned out. (VOY: "Timeless")
In an alternate timeline, the Federation appeared to adapt to this design by the 26th century, utilizing the class in the pivotal Battle of Procyon V. The battle also included the U.S.S. Enterprise NCC-1701-J and a Prometheus Class ship