Been reading up on this at work.
As it stands it's more a PR stunt than anything, the initial 50 cars will be demonstrators to show the technology at work. That technology will filter into the regular line up (the Up! to begin with). My only concern is that a regular Up! wouldn't be the most unproblematic of cars. If they can't get the normal tech to work then I dread to think how the super-tech is going to behave.
Just for reference the XL1 has been in development for probably over a decade, I think the first bulletins appeared somewhere around the Lupo launch IIRC. It is quite astounding to see it finally realised after so long, goes to show the technology is there for ultra efficient motoring if you want it.