Antimatter Engine

Antimatter Engine uses mechanism similar to Atomic and Fussion Engines to generate thrust - namely creating and exhausting created gases - however it is many, many times more efficient. 1/10000 gram of fuel would be more than enough to send small ship from Earth to Mars, with a speed similar to ion-plasma VASIMR drive used today by Outer Colonies ships.
It is a relatively new scientific achievement, at least in terms of making an actually working prototype. The general idea of this engine dates back to XX century, however creating sufficient ammount of antimatter, stabilizing it without causing devastating explosions and making the engine actually works was made possible only by recent technological breakthroughs. Considering the fuel-to-speed efficiency of this engine it is practically bound to replace all of current engine systems, however not in the foreseeable future since the costs of antimatter made using them as a fuel equal to generating thrusts by throwing bags of diamonds offboard.