http://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/
It appears NASA has validated this new space based engine concept and it's looking pretty damn promising.
No massive fuel means your only restriction on acceleration is energy production. We have various long term energy production options already.
They're mentioning 130 year trips to our nearest neighbor solar system based on current propulsion measurements, including slowing down to a stop in system at the other end. Near 10% light speed at the mid point. This is 1000s of years shorter than estimates using current chemical rockets.
4 hour trips to the moon.
~65% reduction in satellite launch weights.
Indefinite mission lengths and redirection capabilities for robotic missions as fuel is no longer required.
There's potential warp drive effects instigated by the same technology that they are looking at. Nothing proven, just slightly supported hypothesis that are good enough to check out if I'm understanding correctly (not a physicist) but exciting none the less.
We still don't really understand how it's working apparently, but it does, and it's glorious. Hopefully it all works out and they can make a practical engine out of it.