[@CowboyCommando]
Modern day: See the EM Drive.

In the roleplay: The Jura use sublight drives on warships. Plus heavily optimized and evolved FTL drives for fast intergalactic travel. The Jura can use antimatter as a source of energy- fusion energy can't beat antimatter. And while not every ship is antimatter, many of them are supported with antimatter-related technologies. Antimatter has a habit of messing up the norm.