Hybridcars.com has a good response to the lawsuit story by a U of Michigan lecturer who had the unique opportunity to directly compare the fuel economy of both the hybrid and non-hybrid Civic - he and his wife own 5-speed versions of each.
The graph shows a couple of things: 1) they're not hypermilers - neither car meeting its original EPA ratings.
2) Their hybrid gets 30% better fuel economy than the regular Civic, which is what Honda advertised in one of its brochures.
Worth a look:
Green Car Expert Gets Real about Honda Civic Hybrid MPG | Hybrid Cars