I did an engineering/R&D internship at Hy-Drive Technologies, they make a hydrogen generation and injection system for large diesel engines (ie, big rigs and buses). The technology (Hydrogen, not the plasma converter crap) really does work and it'* getting better day by day. The system can get the big trucks anywhere from 5-10% gain, even if this 10% is 0.5mpg, the gains in the long run can pay off. Hy-Drive is pretty much at the forefront right now in this regard and my job was really like an episode of Mythbusters, it was my job to help them find ways to make the system better through all sorts of experiments. The trucks aren't completely powered off H2, just bits of it are injected with the intake air.
But the PICC and their so-called hyrogen assist system, combined with the MASSIVE gains they're claiming here... yeah, no.