This is actually the best way I've seen it explained and this is in a round about way the way its largely explained in the TNG Tech Manual:
Michu Kuko had a highlight on new faster then light speed travels in a somewhat recent show (and hell, by somewhat recent, now that I think about it, it was actually last year around Halloween because I remember listening to it on the way to a haunt, but less I digress) but there are actually some really new theories that involve sting theory, though I don't think I can articulate them without burying myself in some wiki articles for a day or so (which mind you, I LOVE doing, but I need to see if I can remember which thread to start on and find some time!)
IIRC the new theory doesn't actually have anything to do with pushing yourself outside the current space domain, or into a subspace domain (which now, I think we seem to be skeptical exists) where energy can either be expended at different levels or thrust requires less energy. It doesn't even involve playing around with excessive amounts of energy. It has to do with the whole idea that the universe is wrapped inside the quantum membrane and actually pushing against that on a quantum level to create speed similar to plucking the strings on a stringed instrument such as a guitar.