This sounds like you might be discussing two different cars.
If the Focus was powered by a hydrogen fuel cell, then it's in an altogether different Group, which would be category A, Group XIV "Hydrogen Fuel Cell Engine". "Class" is weight-dependent. is A few years ago, Buckeye Bullet ran on hydrogen fuel cells, and it still holds some records there. So, it would certainly fit.
As for the Fusion, it sounds like that might have been a normal ICE (piston or Wankel) that just burned hydrogen as i's fuel. If so, then it would be Group XV (blown) or XVI (normally aspirated), and these classes depend on engine size.
But what kind of set up would burn "fuels containing carbon" to power an electrical engine, but which is NOT a hybrid?